Spare decor? Sure. Spare portions? No way. Under the eatery's most distinctive design feature—a colorful wall mural of a lovely Mexican woman (the namesake "bonita")—prepare to gorge on servings that are huge and very cheap. Hash browns, two eggs, pico de gallo and pinto beans pack a breakfast burrito ($5). Likewise, a basic bean, cheese and rice burrito ($3.50) groans with goodness. And a heaping plate of veggie nachos ($6.95) offers a different twist with shavings of carrot atop the artery-clogging pile of chips and cheeses. (HS)