In large bowl, combine oil, water and fajita seasoning mix. Add shrimp; toss to coat. Let stand 30 minutes.
Meanwhile, in medium bowl combine mangoes, onion, pepper, avocado and salsa. Toss to coat; salt to taste. Set aside.
Prepare grill to medium heat. Place shrimp on skewers; discard marinade. Grill shrimp, turning once, until cooked through and opaque (about 8-10 minutes).
Remove shrimp from skewers and place in tortillas. Top with salsa and cheese.
Recipe by A Frugal Chick at https://www.afrugalchick.com/shrimp-tacos-with-mango-avocado-salsa-recipe/