Potato Salad with Avocado Dressing

Name: Potato Salad with Avocado Dressing
Ingredients: 1/2 cup creme fraiche or crema fresca; 1 ripe avocado, peeled and diced; 4 tablespoons fresh lime juice; 1 tablesppon white vinegar; Pinch of chili powder; 1/2 teaspoon ground cumin; 2 garlic cloves, finely chopped; 1 scallion, chopped; 1/2 cup chopped cilantro leaves, plus more for garnish Salad; 1 pint of grape tomatoes, cut in half; 1 small red onion, thinly sliced; Salt and ground black pepper; About 3 pounds of cooked red potatoes, skin on and sliced about1/2-inch thick.