Let the chopped tomato drain in a colander while preparing the rest of the guacamole.
Bring 4 cups water to a boil in a small saucepan. Add the frozen lima beans and cook until tender and creamy, about 5 minutes. Drain the beans and rinse under cold water until cool. Pat the beans dry with a paper towels then remove the skins by pinching the beans so the skins slide off. If using baby limas, you can skip this step.
Scoop out a quarter of the avocado flesh, then process it with the lima beans, lime juice, mayonnaise, and 1/2 teaspoons salt in a food processor until very smooth, 1-1 1/2 minutes, stopping to scrape down the bowl as needed.
Cube the remaining 3/4 of the avocado into 1/2" pieces.
Gently stir the cubed avocado, pureed lima mixture, drained tomato, cilantro, jalapeno, onion, garlic, and cumin together. Season with salt and pepper to taste. Enjoy!
The guacamole can be refrigerated, wrapped tightly in plastic wrap, for up to 48 hours.(the lima beans help keep it very green). Make sure the plastic wrap is touching the surface of the guacamole. Bring to room temperature and season with additional fresh lime juice, salt, and pepper before serving.