Avocado Lime Salad

This is now my favorite salad recipe – discovered over on my favorite recipe site: food.com

3 tablespoons fresh lime juice (1 large lime)
1/2 teaspoon salt, plus
1/8 teaspoon salt
4 small tomatoes, cut in 3/4-inch pieces (2 1/2 cups)
2 medium ripe avocados, cut into 3/4-inch dice (1 1/2 cups)
3 scallions, thinly sliced (white and green parts)
1 large garlic clove, minced
1 tablespoon extra virgin olive oil
1/4 teaspoon ground cumin
1 head boston lettuce, torn into large pieces (8 cups)
1 medium cucumber, peeled, quartered lengthwise, seeded and thinly sliced diagonally (1 cup)
2 tablespoons coarsely chopped fresh cilantro

In a medium glass or ceramic bowl, whisk together 2 tablespoons lime juice and 1/2 teaspoon salt.
Add tomatoes, avocados, scallions and garlic. Using rubber spatula, gently fold to combine.
Season to taste with pepper.
In large bowl, whisk together olive oil, cumin, remaining tablespoon lime juice and 1/8 teaspoon salt.
Add lettuce and toss. Season to taste with pepper.
Divide lettuce among plates. Top each with mound of avocado mixture.
Top with cucumber slices. Sprinkle with cilantro and serve.