Phnom Penh Restaurant is the singular spot on this list. 1010 North Minnesota, two blocks south of Thai10, in a one-story building that looks like a converted small house. 4.6 stars across 650 reviews, which puts the rating between Pho Thai Downtown's volume play and Thai10's quality play, and the menu is unlike anything else in the city — Cambodian, Thai, and Vietnamese in one room, run by an owner who cooks and a kitchen that knows what it's doing across all three traditions.
The hours are the tell. Closed Sundays and Mondays. 11 AM to 2 PM, then closed for the afternoon, then open again 4 PM to 8 PM. That mid-day closure between 2 and 4 is the signature of an owner-cooked kitchen — the chef takes a break, the prep happens, the dinner service starts fresh. Most American restaurants don't do this because most American restaurants are operated by managers, not by cooks. Phnom Penh is operated by a cook. Plan around the schedule.
The orders. The drunken noodles are the headline — a different version than Pho Thai's, with different spice profile and slightly different aromatics, and worth ordering for comparison if you've already had Pho Thai's. The pho is excellent, full stop. Not just "good for Sioux Falls" — actually good, the kind of broth that has been simmered the right length of time, with the right bones, with the right balance of star anise and clove and ginger. If you've had pho in a major coastal city and want to find a Sioux Falls version that holds up, Phnom Penh is where you start.
The Cambodian end of the menu is the part most diners don't explore, which is a shame. Ask the kitchen what's on for the day. Khmer-style noodle soups (kuy teav, num banh chok), the lok lak (Cambodian stir-fried beef), the amok if it's available — these are the orders that make Phnom Penh singular in the city. There is no other Cambodian kitchen in Sioux Falls. If you want to know what Cambodian food is, this is the only place to find out, and the kitchen will tell you what's good today if you ask.
The room is small and unfussy. A handful of tables, fluorescent lighting, no music, no design. The aesthetic is the food. The food is what carries the room. Bring a date here only if your date understands that the room is incidental and the bowl is the event. Otherwise, save Phnom Penh for the meal where you don't need the dining room to perform.
Parking is the small lot in front, plus the residential side streets. Easy.
For takeout: Phnom Penh's to-go is reliable but the pho doesn't travel well — same problem as everywhere, the noodles overcook in the broth on the drive home. Get the noodle dishes for takeout, drink the pho on premises. The drunken noodles travel fine. The Cambodian noodle soups should also be eaten on premises if you've never had them, because the experience of building the bowl with the herbs and lime and chili at the table is part of the dish.
Card and cash. The phone is (605) 332-3935. There is no standalone website. The Facebook page is the operating presence, and the hours posted there can lag the actual hours. Calling ahead is a good idea, especially if you're driving across town.
The kitchen turn is medium-paced. This is not a fast-casual room. Lunch can take 25 to 30 minutes for a noodle bowl, dinner closer to 35. Plan accordingly. If you have a tight schedule, eat somewhere else.
Compared to Pho Thai Downtown: same general menu universe, very different execution. Pho Thai Downtown is the breadth play — five cuisines under one roof, optimized for groups that can't agree. Phnom Penh is the depth play — three cuisines under one roof, executed by someone who's cooked them their whole life. If you're choosing between them on a given night, the question is whether you want optionality or authenticity.
Compared to Thai10 (two blocks north): Thai10 is more strictly Thai. Phnom Penh is more pan-Southeast-Asian, with Cambodian as the differentiator. Both are kitchen-driven; both are owner-operated; both should be on your rotation. They are not in competition. They serve different needs on different nights.
If you've never been: order the pho dac biet, the drunken noodles, and one Cambodian dish recommended by the kitchen. That's the introduction. About $40 a head. Worth it.
If you've been before and want to go deeper: skip the pho (you've had it), order two Cambodian dishes, and ask the kitchen what's new. The owner cooks, and an owner-cook responds to "what should I order today" with a real answer.
The "best-kept secret" framing. Locals will tell you Phnom Penh is the best-kept secret in Sioux Falls. It's not a secret — 650 reviews is not a secret — but the local convention is to call it one, and I'm not going to fight the convention. The convention is right that the food is exceptional. The convention is wrong that nobody knows. The right reading is that Phnom Penh is the city's best-loved authentic Southeast Asian kitchen, and the people who love it tend to feel personal about it. Which is the right way to feel.
The bottom line. If you're choosing one spot on this list to drive across town for, Phnom Penh is in the top three. The afternoon-closure schedule is the cost of admission. Plan around it. The food is worth it.
The owner cooks, and an owner-cook responds to "what should I order today" with a real answer.