In a molcajete, use the tejolote (lava-stone pestle) to grind the garlic, onion, jalapeño, and salt until all the ingredients are well ground.
Dice the avocados and gently fold into the garlic-onion- chile paste, keeping the avocados fairly intact.
Add tomatoes and squeeze the lime juice over the avocado and gently stir until the mixture is chunky.
Taste and add salt, if necessary. Serve immediately, directly from the molcajete, with tortilla chips.
Notes
For a healthier version, serve with cut up veggies or baked tostadas instead of fried tortilla chips.
Make ahead tip: Avocado oxidizes (turns brown) when exposed to oxygen for too long. Prep any of the ingredients as early as you like, but leave the avocado mashing until the last minute.