Shrimp Cocktail Tostadas

Place shrimp in resealable food-storage plastic bag, and squeeze the juice of half the lemon into the bag. Add lemon peel, canola oil, cumin, garlic powder, salt, pepper and 1 tablespoon of the cilantro. Seal bag, and gently coat shrimp. Place bag on plate in refrigerator to marinate, at least 10 minutes but no longer than 20.

Meanwhile, heat grill to medium-high. While shrimp marinates and grill heats, mix remaining 1/4 cup cilantro and onion in small bowl. In another small bowl, mix cocktail sauce, salsa and juice of remaining lemon. Add half of the cilantro mixture to the cocktail sauce mixture. Set aside.

Place shrimp on grill. Cover and cook about 2 minutes on each side or until just done and shrimp has turned pink and opaque throughout. Remove shrimp to a bowl until cool enough to handle. If there are tails on the shrimp, remove them, and chop the shrimp into bite-size pieces. Add chopped shrimp to cocktail sauce mixture, and stir to coat. Spoon onto tostada shells, and top with remaining cilantro mixture and whatever garnishes you like.