If there is one institution that has retained respect in Washington over the years, it is the Omega Restaurant on Columbia Road. Savory peasant food from Spain and Latin America, with big portions and little prices. As happens in that business, the restaurant was sold a couple of years ago. But the original owner (and cook) has now opened a carry-out with what seems like the original food at the original prices. Casa Baez, as it is called, has about thirty main dishes from which to choose, ranging from huge cornmeal tamales and pasteless stuffed with bits of meat (authentically leaden - sixty to seventy-five cents) to platters of crispy pork masitas or a half a fragrant roast chicken with marinated onions on a mound of rice, with a full pint of black beans ($2.50 per platter). Their tacos (sixty to eighty cents) are spicy, their codfish fritters (twenty cents) chewy, unctuous, wonderful. If you like the oily tartness of escabeche, they have it ($1.50), as well as fried plantains and tortillas and chili. Some of the dishes - arroz con mariscos or paella - cost over $4 and take thirty-five minutes. But everything else is ready quickly. Check the daily specials; caldo gallego, a thick soup with ham, beans, potatoes and greens, was a perfect midwinter meal at $1.10. And if you order ahead, they will even roast you a whole suckling pi