Partially mash avocados with a fork on a cutting board or in a large bowl, pour lime juice over top and continue to mash to reach desired consistency. Transfer to a mixing bowl. Run chopped red onions under cold water (to remove harsh bite from onion), drain well and add onions to avocado mixture, along with garlic, cilantro, cayenne pepper and season with salt and pepper to taste. Stir to combine and fold in diced tomatoes. Serve with tortilla chips or as a topping on your taco's.Thank you, Cooking Classy, for such a fresh guacamole recipe!