El Caporal is the long-standing Mexican restaurant Ellensburg students bring their parents to. It is in a low building on West 8th Avenue near the university; the dining room is unremarkable but the kitchen turns out an excellent carne asada plate, decent enchiladas, and a strong margarita.
Portions are generous, prices are college-town reasonable, and the place is busy most evenings — get there before 7 if you want a quick table. Good for groups.