Cilantro Cream Sauce: Purée garlic with salt. Combine sour cream, onion, cilantro and sugar. Add garlic mixture and stir gently to blend well.
Enchiladas: Heat tortillas, 1 at a time, in oil until soft. Place 1/4 cup crab meat in center of each tortilla, then sprinkle with 1 tablespoon onion. Spread a little Salsa Con Tomatillos on top. Roll enchiladas, and place, seam-side down, in shallow baking dish. Cover with remaining Salsa Con Tomatillos. Sprinkle generously with cheese.
Bake at 400° F about 10 minutes, or until hot and cheese melts. Serve with dollop of Sour Cream Sauce, and garnish with olives, avocado and tomato slices.
Makes: 6 enchiladas