Mahi Mahi Tacos with Mango-Pineapple Salsa

For the Mango-Pineapple Salsa:

• ¾ cup mango, diced
• ½ cup pineapple (fresh or canned), diced
• 2 tablespoons red onion, diced 
• 1 jalapeño, seeded and diced
• 2 tablespoons fresh cilantro, chopped
• 1 tablespoon fresh lime juice
• ¼ teaspoon salt (optional)

For the Cilantro-Lime Crema:

• ¼ cup sour cream
• 2 teaspoons fresh lime juice
• 1 tablespoon cilantro

For the Mahi Mahi:

• 1 ½ teaspoons salt (optional)
• ¾ teaspoon black pepper
• ½ teaspoon chili powder 
• 1 tablespoon olive oil
• 12 ounces mahi mahi (about 2 fillets)

For the Tacos:

• 6 small flour tortillas
• ½ head iceberg lettuce, shredded
• Lime wedges, for serving (optional)