1Reserve 1 tablespoon fresh lime juice. Combine the remaining lime juice with the chili powder and olive oil. Add a pinch of salt. Add shrimp and mix well to coat in the marinade.
2While the shrimp marinates, cut the tomatillos in half and place them cut side down on a baking sheet lined with foil. Broil under broiler for about 5 minutes, until the skins turn slightly black. Remove tomatillos from the oven.
3Add broiled tomatillos, 1 tablespoon lime juice, onions, jalapeno, and a pinch of salt to a blender or food processor and process until well mixed but still slightly chunky. Check seasoning and add more salt if needed. Put in the refrigerator to chill slightly.
4Stir shrimp in marinade the make sure they are well-coated. Grill the shrimp in a grill pan or on a gas or charcoal grill until just pink and cooked through.
5Add about 1/2 cup of the salsa verde to the bottom of a shallow serving bowl. Take 4 to 6 of the shrimp and place them tail up in the salsa, with the tails touching so the shrimp stand tail up in the salsa and serve.