1. Cook lobster in boiling salted water to cover in a Dutch oven 6 to 7 minutes Remove from liquid, reserving boiling liquid in pot. Cool lobster.
2. Add corn to reserved boiling liquid, and cook 3 minutes. Remove corn; measure 2 cups cooking liquid, and set aside.
3. Remove lobster meat from shells, reserving shells. Chop meat.
4. Cut corn from cobs, reserving 2 corncobs. Loosely measure 1/4 cup cilantro leaves; chop and set aside.
5. Melt butter in a Dutch oven over medium-high heat. Add 3/4 cup chopped onion and 2 jalapeño peppers; sauté 2 minutes. Add reserved lobster shells, reserved corncobs, reserved 2 cups cooking liquid, remaining cilantro, whipping cream, and 1 teaspoon salt. Bring to a boil; reduce heat, and simmer 10 minutes. Pour mixture through a wire-mesh strainer, discarding solids. Cool cream mixture slightly.
6. Process cream mixture, 1 avocado, and 1 tablespoon lime juice in a food processor or blender until smooth, stopping to scrape down sides. Set cream sauce aside.
7. Chop remaining avocado, and place in a small bowl. Stir in corn kernels, remaining onion, remaining jalapeno pepper, remaining 2 tablespoons lime juice, tomato, and cumin. Set 1 cup corn relish aside.
8. Stir lobster, sour cream, and remaining 1/2 teaspoon salt into remaining corn mixture.
9. Warm tortillas according to package directions. Place 1/2 cup lobster mixture down the center of each tortilla; roll up tortillas and place, seam side down, in a 13x9 inch baking dish coated with cooking spray. Top with cream sauce, spreading to cover edges of tortillas.
10. Bake at 350° for 22 minutes. Sprinkle with reserved 1 cup corn relish and reserved chopped cilantro. Serve immediately.
11. * 1.5 pounds unpeeled, large fresh shrimp may be substituted for lobster.

*Large avocados are recommended for this recipe. A large avocado averages about 8 ounces. If using smaller or larger size avocados adjust the quantity accordingly.