Lilac

4.5 out of 5 stars. Food here is a home run derby and reasonably priced for the quality. Half star deduction is for the rather terse head waitress who was certainly not overwhelmed, but made us feel like we were rolling in with a gang of 40 people.  Menu changes regularly, but if you find yourself here in May 2013, the following is highly recommended:
Appetizers: shrimp curry and goat cheese soufflé.
Entrees: lamb sausage w/ pasta, glazed pork, and burger w/ bacon jelly.
Desserts: one of every kind they have - Tres Leches w/ huckleberry, olive chocolate cake, and one whose name I forgot.

Other entree: roasted chicken - nothing special, and paradoxically more expensive than many of the tastier options.

Decent wine list.

I really wanted to like Lilac...I had heard wonderful things. I went with some friends for my birthday dinner and we were all underwhelmed, but I will speak only to what I ate. The crab hush puppies were good, but not great, and the pork belly was mediocre compared to others I have had. I was most disappointed in the entrees. I ordered the chicken and was told by the waitress that it was "phenomenal". Well, it was not love at first bite. The chicken was dry and very overcooked. The accompaniments were fine, but the portion was ridiculously small for the price. My friend had the pasta with sausage, which I sampled. The sausage was dry and crumbly, not juicy as a sausage should be. The pasta was good, but a small amount.I am not someone who loves large portions and eats a ton, but I left hungry. I hope to give it a second chance and have a better experience, but for now I will approach Lilac with caution.

Far and away the best meal I've ever had in Billings, and definitely in the top ten for the whole state. Crab stuffed hush puppies, pork belly wraps, sous vide steak with black garlic, and more pork belly, this time with rye gnocchi. Aside from some minor, nitpicky quibbles about the food, it was excellent. As far as I know, these folks are the only ones doing sous vide in Montana, but I could be wrong. They, however, are doin it right.The service and wine and beer selection were fantastic as well.

It is a small place, with a small kitchen, and an appropriately sized (and ever-changing) menu, so you might want to call ahead, or sit at the bar.