In a medium bowl, mix together the oil, chili powder, cumin, lime juice, cilantro and salt. Add shrimp to bowl and toss to coat. Let shrimp marinate in the refrigerator for about 10-15 minutes.
While the shrimp are marinating, combine mango, avocado, onion, cilantro, and lime juice in a medium bowl. Mix well.
Heat the grill over medium-high heat. Add the shrimp to the grill and cook until opaque and cooked through, about 2-3 minutes per side.
Divide the salsa and shrimp evenly among the tortillas and top with any other toppings as desired.
Notes
Prep the salsa in advance without the avocado. Store in the refrigerator and add chopped avocado just prior to serving (to prevent avocado from turning brown.)
Add your other favorite toppings like sour cream, cheese, jalapeños, etc.