Cut four sheets of foil, about 12-inches long. Divide shrimp, bell peppers and onion into 4 equal portions and add to the center of each foil in a single layer.
Fold up all 4 sides of each foil packet. Add olive oil, taco seasoning and lime juice; gently toss to combine. Fold the sides of the foil over the shrimp, covering completely and sealing the packets closed.
Place foil packets on the grill and cook until just cooked through, about 10-12 minutes.*
Served immediately with tortillas, garnished with cilantro, if desired.
Notes
*This can also be baked for 12-15 minutes at 400 degrees F.