Shrimp Tostadas

1 pound cooked bay shrimp
1 3/4 cups (14.5 ounce can) diced tomatoes, drained
1 cup (1 small) chopped white onion
1/2 cup (4 ounce can) diced green chiles
1/4 cup chopped fresh cilantro
3 tablespoons vegetable oil
3 tablespoons lime juice
1 3/4 cups (16 ounce can) refried beans with jalape?os, warmed
1 (10-count) package tostada shells, warmed *
2 1/2 cups shredded romaine lettuce

* or fry corn tortillas flat

Combine shrimp, tomatoes, onion, chiles, cilantro, vegetable oil and lime juice in medium bowl; cover. (May be prepared ahead and refrigerated.)

Spread about 2 tablespoons beans over each tostada shell. Top with 1/4 cup lettuce and 1/2 cup shrimp mixture.