Prepare the dressing: In a small non-reactive bowl, whisk together the fresh lime juice, minced garlic, ground cumin, sea salt, and black pepper until the salt is fully dissolved and the mixture is emulsified.
Process the vegetables: Seed the Roma tomatoes before dicing to prevent the salsa from becoming watery. Dice the avocados last to minimize exposure to air and prevent browning.
Combine base ingredients: In a medium glass or stainless steel mixing bowl, combine the diced tomatoes, red onion, minced jalapeño, and chopped cilantro.
Add avocado: Gently place the diced avocado on top of the tomato mixture.
Emulsify and coat: Drizzle the prepared lime dressing over the avocado and vegetables immediately.
Fold: Using a silicone spatula, use a gentle folding motion to combine the ingredients until the avocado is evenly coated with the dressing. Avoid over-mixing to maintain the structural integrity of the avocado cubes.
Meld: Allow the salsa to sit at room temperature for 10-15 minutes before serving to allow the flavors to harmonize, or serve immediately for maximum brightness.