1. Combine 1 tablespoon olive oil, 2 teaspoons lime juice, cumin, paprika, and red pepper in a small bowl. Combine shrimp and spice mixture in a zip-top plastic bag, and seal. Let stand 15 minutes.
2. Combine 1 1/2 teaspoons oil, 2 teaspoons juice, onions, 1/8 teaspoon salt, rind, apple, and jalapeño; toss.
3. Remove shrimp from bag; discard marinade. Heat a grill pan over medium-high heat. Sprinkle shrimp with 1/8 teaspoon salt. Arrange half of shrimp in pan; grill 2 minutes on each side or until done. Remove from pan; keep warm. Repeat procedure with remaining shrimp. Toast the tortillas in grill pan, if desired. Place 2 tortillas on each of 4 plates, and divide shrimp evenly among tortillas. Divide salsa evenly among tacos, and top with queso fresco.