Roasted Sweet Potato and Okra Salad

Name: Roasted Sweet Potato and Okra Salad
Ingredients: 1 pound red potatoes, scrubbed but not peeled and cut into 1-inch cubes; 3/4? cup plus 1 tablespoon extra-virgin olive oil; Salt and freshly ground pepper; 3 pounds orange sweet potatoes, peeled and cut into 1-inch cubes; 1 tablespoon mustard seeds; 5 ounces spinach, large stems discarded, leaves rinsed (8 cups packed); 1 pound small okra, thawed if frozen; 1/4 cup plus 1 tablespoon red wine vinegar; 3 tablespoons drained and chopped capers