How to Make It
Place fish in a glass or ceramic bowl. Give the salsa macha a good stir to evenly distribute all ingredients. Pour salsa macha over fish, and stir gently with a spoon until the fish is completely coated. Season with salt. Let stand 5 minutes.
Gently stir in the cucumber, onion, and avocado. Add lime juice. Taste and add more salsa macha or lime juice, if desired. Stir in cilantro just before serving. Season with additional salt, and serve immediately with tostadas.