This is my husband's recipe - it's especially good with scallops. I prefer it with the serranos and the chiles together.
1 pound fresh fish or scallops
1 cup fresh lime juice
1 small onion
1 can green chiles or 3 pickled serrano peppers, rinsed
seeded, and cut in strips
1/4 cup olive oil
3/4 teaspoon salt
1 teaspoon dried oregano, crushed
1/8 teaspoon pepper
2 medium tomatoes
1/4 cup chopped fresh cilantro
1 teaspoon jalapeño juice (optional)
Cut fish into 1/2 inch cubes. In a non-metal bowl cover cubed fish with lime juice. Cover and refrigerate 4 hours or overnight or till fish is opaque, turning occasionally. Thinly slice the onions, separating into rings. Add to fish with chiles/peppers, olive oil, salt, oregano, and pepper. Toss gently to combine well; chill. Peel, chop tomatoes; toss with chilled fish mixture--add jalapeño juice and snipped cilantro. Makes 10-12 appetizer servings.