Add the avocado halves to a medium size mixing bowl. Squeeze the lime juice over the avocados and toss well to coat. Add the cumin. Now grab a fork and lightly mash the avocados. I like to keep my guacamole on the chunky side. Next fold in the diced onion, chopped jalapeño, grape tomatoes, cilantro and a pinch of salt and pepper. Taste and season with more salt and pepper if desired. Grab some chips and dig in!