On a whim decided to try the vegetarian tofu Rueben. Really tasty and gave the same overall impression as a corn beef Rueben without the stringy meat part. I was skeptical about getting it but would do it again for sure. I am not a vegetarian btw.

Boulder Creek side hot dog 🌭 stand. With indoor, outdoor parking lot and creek side blanket dining options.

Oh this wonderfully delicious place. In terms of food, It is one my all time guilty pleasures. For those who passing through Boulder it’s easy to miss. And parking can sometimes be difficult because of the small amount of spaces. But it is worth every inconvenience. It is situated right above Boulder creek so you can take your meal, eat and enjoy the view. This place has been here since as long as I have been born. If you are looking for an amazing Chicago style dog, you are in the right place. They also serve burgers, and some other items. But I just can’t go there and not grab two delicious dogs. With a great selection of condiments and greasy, heavenly fries, you really can’t go wrong. Unless you drop your bag of fries, which is a travesty. I would know because, I have felt this pain. I almost broke down. And even thought about digging in anyway (well not really but the pain is real). Luckily, returning to Mustard’s and explaining the atrocity I just committed. They hooked me up with a new bag of these delicious fries. The interior of the building is cute and pops with character. It honestly looks like a joint you would stop at in Chicago. I have been to many small place like this in my time living in Chicago. The interior has remained the same since I can remember. Mustard’s is just full of character. This place has been a Boulder staple that reaches back to the earlier days of Boulder, before it became so built up. Whether you are a local or just passing through, this place is a must!

Cool to see a local place that still feels like old Boulder! Great food, and good pricing. Got the double cheeseburger and it was wonderful, and my girlfriend got a German sausage sandwich. She said it reminded her of German food back in the Midwest. The exterior patio has a great view of the flatirons and has covered seating.

I had my first Chicago style, vegatarian hot dog, and it was just delicious. Thank you for making a lovely plate of food while nourishing my memories of my childhood home.

Ordered Chicago dog with added Mayo. Just got a hot dog with just Mayo. Also ordered fries with $3 of dipping sauce and didn’t receive fries. Careless presentation of food. Usually don’t take the time to write a extensive review but felt this was needed.

Love this place. Hole in the wall vibes with the best bunwhiches in town. Super friendly staff, too. Go for the German brat' and get all the recommendeds. Untouchable.

Funky as ever, Mustard's continues to crank out the best damn Chicago dog around. Paired with their hand cut, fresh fries, it's a real treat. Situated close to the creek and lots of downtown Boulder park space, it's easy to grab and go sit outside by the creek, or enjoy the old school interior. Went a week before taking a kid to Chicago for school, and we hunted down a fantastic Chicago dog spot in the city. Mustard's holds its own Vegetarians: the tofu Reuben is a revelation and actually the only thing I get. If the cheese is on your menu, get it loaded and enjoy. It's hard to believe Mustard's soldiers on after all these years and changes in Boulder. Get in for a real slice of 'old Boulder'.

It's been so long since I last ate here, and it's just as awesome as I remember. The food is still incredible. Worth the short wait. Has outdoor seating as well as indoor. Service is friendly and prompt, didn't have to wait that long for m food. I'll be back sooner rather than a n later. I highly recommend this place.

Exceptionally good hot dog, very nostalgic for me. As a kid, I used to go to a Lowes near my house that had these in a stand outside. Was super excited to hear they still existed. Drove a long way just to get here and wasn't disappointed! The hot dog was absolutely fantastic. However, the location was extremely tiny and didn't leave a lot of room for much of anything. Furniture is kid sized, which was odd. Place didn't seem to have its own parking, which is fair, but we had to pay for parking nearby. The hot dog was great, although rather expensive for a hotdog.

I came in today for lunch, I was the only person in the store while there was at least four people behind the counter I waited at least 10 minutes before I had to leave because I did not receive any service. I would have loved to try a dog today as they looked pretty decent. It's unfortunate that you have such and unattentive staff. Hopefully there is some respectful people working if I ever decide to stop in again.

I used to go here all the time for vegan dogs and a can of Old Style. The food is amazing, the location is perfect, and the service is excellent! I live in Denver now so I haven't been by in a long time. I was in the area a few days ago and they still remembered me! So nice!

Absolutely amazing Italian beef, not just for the area, but a great contender for the Chicagoland area, too! Small place with a straight forward yet versatile menu and an efficient and friendly staff. We will absolutely be back to try more of the menu!

As soon as you walk up to the door, yummy smells linger. After walking in it’s has a throwback cozy ambience that smells even better!! I really enjoyed the chili cheese dog and chili cheese fries. My friend got the classic Chicago dog which also looked incredible. Staff is chill. I’ll be back again! Great Chicago comfort food with cool signage and Chicago vibes. Go White Sox!!!

We're from the Chicago area and it was great to get the quality and better service with a smile than Chicago. So pleasant, beef was great but get the large or better if you want more than 3 bites.

A Boulder staple, Mustard's is THE hot dog stand. Delicious dogs, and if you aren't in the mood for a hot dog try one of their delicious burgers or mouth-watering fries. I personally go with the Polish sausage.

Pretty regular hot dog for the price. Chilli cheese fries were just okay. Grilled cheese was a little burnt. Just kind of m'eh overall

I've been coming here for 30+ years and it's hardly changed, which is a good thing! I love supporting a small family business that still makes excellent burgers and fries in a cozy spot. So glad you guys have survived the past few years.

I recommend the Chicago dog with fries! The chicken sandwich was great but small for the price. Very clean seating area and bathrooms. Friendly staff told us we could borrow a blanket and have a picnic by the river.

Excellent Chicago style dogs and hot beef from 2 former Chicagoans. I'm impressed they had veggie dogs. Twas delish. If you get fries, get some nacho cheese on the side. Friendly staff, nice and clean restaurant.

Best hot dogs in the world. Get the hot peppers! They aren’t that hot… Good fries also.

Classic Chicago style hot dogs, and done well! The atmosphere is just what you would expect, and want, from a hot dog place. Kids loved the food as well and French fries were very tasty. Definitely worth a try!

I'm very grateful for this place. I love their veggie soy dog and their large fries. Love that they have gluten-free and vegan options. Mustard Stand is a wonderful place to dine in at. Anytime, I am in need a of filling and quick bite. Between rushing place to place, I know to always come to Mustard Stand to fuel ⛽ up. Thank you for existing!!! ✌️😋🌈

Still the best around, "Chicago Style" hot dog, in Colorado! Greatest dog with no 21st century foolishness...in other words this is an authentic "Chicago" dog complete with sport peppers, onions, poppy seed bun, dill pickle, et al. Vintage "Vienna beef hotdog stand" photos fill the wall by the cashier stand and you can see the cooks build your meal. Good, greasy cheeseburgers, fries and Polish sausage too. You can sit outside and people watch or get a picnic lunch to go, for some creek side dinning. It's sometimes crowded during home football season or events in the park across the street. The prices are fair considering they are in the land of Boulder.

This is the real deal. Get the Chicago dog with the poppy seed bun and the fries and a Coke. It isn't a copy of a Chicago hot dog, it IS a Chicago hot dog. Well done sir!

Soy dog is nothing special. At many vegan restaurants in Boulder I feel like I’m eating something I couldn’t replicate at home. Their hotdog is something I have made but better at home.

Mustard's Last Stand is a childhood staple for me. I have been coming here since. I was a kid as did my dad before. It's nothing fancy, just good dogs. Staff has always been friendly and efficient. I am heart broken they are knocking it down. I say knock down the attached office building and keep Mustard's! It's a Boulder classic that should be kept. Great place to grab lunch and enjoy the park. Keep Boulder history alive!

I know, I know... I shouldn't have ordered a burger at a hot dog shop. But, if it's on the menu, I can have it, right? The burger was overcooked, dry, and overall not very good. Fries were not great either. The only good thing about this place was the convenient location right by the Boulder creek, making it a nice option for food to eat on a riverside picnic.

Came in for a true chicago dog and not disappointed. A great snap to the dog, and it's on poppy seed buns. All I miss is henning it served up in a paper bag with greasy fries in the bottom