Place diced avocados into a large bowl. Squeeze juice from half of a lime over the avocados to prevent them from browning.
Slice the tomatoes in half lengthwise and scoop out the seeds and juices, so just the firmer flesh remains.
Dice tomatoes and add them to the bowl, along with the finely minced cilantro, jalapenos and onions. Season with 1/2 teaspoon of salt and 1/4 teaspoon of black pepper and stir to combine well.
Add lemon juice, more lime juice, and salt and pepper to taste.
Serve with tortilla chips, tacos, burritos and more.
Notes
Know your avocados. You want Haas avocados that are nice and ripe, but not over ripe. In the store, give the avocados a little gentle squeeze in the palm of your hand (using your finger can bruise the flesh). You want the avocado to have some give to it, but still be slightly firm and not at all mushy. If all that is available are hard avocados, take those and place them in a paper bag for several days to speed up the ripening process.
Texture is important. Slice the avocados in half, remove the pit and scoop the flesh into a large bowl. You can slice it in the skin if you want, but your hands get pretty slippery and it just tends to make more of a mess than it’s worth. Mash the avocado gently with a pastry cutter, potato masher or a large fork until your guac is just slightly chunky. Those chunks give your guac texture so you want them there. Make sure to finely dice the onion, cilantro and jalapenos so they will mix well with the avocado.