Slice avocados in half lengthwise and scoop the flesh from the skin with a spoon. Place avocado in a mixing bowl.
Squeeze lime over the avocados. Add salt, cumin, and chili powder.
Use a fork (or potato masher) to mash the avocado to desired consistency – you can make a chunky guacamole or mash it as smooth as you'd like. I personally like a bit more chunky guacamole.
Add the chopped cilantro and diced tomatoes and stir to combine. Serve guacamole immediately with chips, veggies, or your favorite Mexican dish!