To prepare dressing: In measuring cup, combine oil, pepper, garlic, cumin, salt and lime juice. Dice 1-1/2 of the avocados; place in a small bowl; toss with 2 tablespoons of the dressing. Cut remaining avocado half in slices; place in a pie plate with shrimp; coat with remaining dressing. To serve: Line 4 martini or wine glasses with lettuce leaves. Spoon diced avocado mixture into glasses. Top with shrimp and avocado slices. Spoon any remaining dressing over avocados and shrimp. Recipe can be doubled.