Romaine Salad with Avocado-Lime Dressing

½ ripe avocado
5 tablespoons buttermilk
2 tablespoons lime juice

1 tablespoon extra-virgin olive oil
½ teaspoon ground cumin
½ teaspoon salt
3 romaine hearts (3-4 ounces each)
1 cup sliced cherry tomatoes
Freshly ground pepper to taste

Puree avocado, buttermilk, lime juice, oil, cumin and salt in a food processor or blender until smooth.
Cut romaine hearts in bite sized pieces. Serve topped with the dressing, tomatoes and pepper.