Preheat oven to 425 degrees F. Spray cups of a 24 cup mini muffin tin or a standard size 12-cup muffin tin with nonstick cooking spray.
To make tortilla cups: Using a 3 inch cookie cutter or cup, cut about 8-9 medium circles out of each tortilla. Brush each circle with olive oil or spray with cooking spray. Press each circle into a muffin cup. Bake 10-12 minutes or until cups are golden and crispy.
To make guacamole: In a medium bowl, mash together the avocados. Mix in onion, tomatoes, cilantro, cayenne, salt and lime juice. Stir until fully combined, cover and set aside in the fridge until ready to use.
To cook shrimp: Combine shrimp with taco seasoning in a large bowl or ziplock bag. Heat a large heavy-duty or cast iron skillet on high heat for 2 minutes. Add the olive oil and shrimp. Cook shrimp in a skillet on medium-high heat until pink and cooked through, about 5 minutes. Remove from heat and set aside.
To assemble: Fill each mini tortilla cup with about 1 teaspoon of guacamole (use 2 tablespoons for regular size cups). Top guacamole with 1 shrimp and sprinkle with a squeeze of fresh lime juice. Serve immediately.