1. In a bowl, pour boiling water over the tomatoes. Let stand 30 seconds and drain. Slip off the skins and cut the tomatoes in half. Squeeze out the seeds and chop coarsely. Squeeze out the remaining juice and discard or reserve for another use. Transfer to a bowl and stir in the cilantro, onion, garlic and lime juice.
2. Chop the jalapeno peppers finely, being careful to wash your hands afterward to avoid burns. Remove the seeds. Stir the peppers into the tomato mixture.
3. When ready to serve, mash the avocados coarsely with a fork or potato masher (do not puree) and fold them into the tomato mixture. Cover the surface of the Guacamole with plastic wrap between servings to prevent it from darkening. This will make about 1-1/2 cups.