Select mangoes that yield slightly to gentle pressure – they should feel soft but not mushy. Cut around the large flat pit, score the flesh in a grid pattern, then turn the skin inside out to reveal perfect cubes. Slice these off and into your bowl.
Choose avocados that yield to gentle pressure but aren't too soft. Cut around the pit, twist to separate halves, and remove the pit. Score the flesh in a grid pattern without piercing the skin, then scoop out the cubes with a spoon. Immediately toss with a tablespoon of lime juice to prevent browning.
Add red onion, jalapeño, cilantro, remaining lime juice, salt, and pepper to your bowl with the mangoes and avocados. If using garlic, add it now. Fold the ingredients gently rather than stirring vigorously to maintain the integrity of both the mango and avocado pieces.
Taste and adjust seasonings as needed. For optimal flavor development, cover and refrigerate for at least 30 minutes before serving. This resting period allows the flavors to meld while maintaining the refreshing temperature perfect for hot summer days.