A man whose opinion we highly respect once likened the idea of stuffing rice into a burrito to serving spaghetti with a side of mashed potatoes--a definite starch overload. The folks at El Burrito Mercado tend to agree, noting a subtle but nonetheless significant difference between a side order of rice and a burrito filled with the stuff. It's advice like that that has kept this authentic Mexican cafeteria/grocery store--situated in St. Paul's District del Sol--tops in our book for what seems like the last decade. Inside, the ambience is just as charming and authentic as the food itself. Everything from piñatas to a portrait of Frida Kahlo hangs on the orange-colored walls and ceilings, and Mexican pop music reverberates throughout the cafeteria as you choose between the spicy chicken or beef for a made-to-order burrito wrapped in a warm, 12-inch flour tortilla. Wash it all down with either a Mexican soda or a smooth, sweet agua fresca, then finish your meal with a slice of fresh tres leches cake or rich rice pudding. The accents are delightful here, but make no mistake: At El Burrito Mercado, it's the burrito that rules the roost.