Season shrimp with salt, pepper and cumin powder. Cook in a lightly oiled skillet. Then place in a bowl, along with avocado, tomatoes, jalapeño, garlic, red onion, cilantro and lime juice. Mix well and chill in the fridge.
Peel and slice plantains into 3-inch chunks. Fry in 350F oil until slightly golden, but not browned, for about 4-5 minutes.
Immediately place one fried plantain chunk each in a greased muffin pan well. Using a pestle or shot glass, gently press to form a cup.
Fry again until golden brown. Drain on paper towel, and lightly season with salt.
Immediately fill the cups with the shrimp mixture and serve.