Mesa Grill's Southwestern Potato Salad

1 1/2 cups prepared mayonnaise

1/4 cup Dijon mustard

2 tablespoons fresh lime juice

2 tablespoons chipotle pepper puree

1 large ripe tomato, seeded and diced

1/4 cup chopped cilantro leaves

3 scallions, chopped, white and green parts

1 medium red onion, thinly sliced

1/2 teaspoon cayenne

4 cloves garlic, finely chopped

Salt and freshly ground black pepper

16 new potatoes, about 3 to 4 pounds, cooked, drained and sliced 1/2-inch thick