Dzirnavu 76 (near west corner of Krišjana Barona iela)
breakfast buffet M-Sa 0800-1100
Dzirnavas (the name means mill) is part of a chain of buffet-style places that includes Alus seta at Tirgonu iela 6 and Vermanitis at Elizabetas iela 65 (corner Terbatas iela). They all look like Mövenpick (the Swiss cafeteria chain) restaurants. Like Mövenpick, you pick up a tray and visit a series of food stations to choose your food, then pay the cashier which you pass before you get to a table.
However, Dzirnavas is the one to go to at breakfast, because they are they only ones who have a breakfast buffet deal. Between 0800 and 1100 every day except Sunday, your food bill maxes out at Ls. 2.50 ($4.50), which covers all the food you can eat and a bottomless cup of coffee or tea. Juices are extra, and pricey: Ls 0.60 ($1.06) for carrot, Ls 0.80 ($1.42) for orange. You can really get nickel and dimed by little items (Ls. 0.20 for honey, 0.10 for sour cream, and so forth), so the Ls. 2.50 breakfast buffet is a great deal.
Unlike a lot of places they do fire up the lunch stations at breakfast time, and you can have any of the lunch entrees as part of your breakfast buffet. They serve the usual breakfast foods (eggs, bacon, sausages, oatmeal), as well as Latvian/Russian food like shashlik for lunch.
The staff are helpful and some speak English, which is good because everything is labeled in Latvian.