Combining a variety of field peas, such as black-eyed peas, speckled butter beans, and lady peas, gives additional color and texture to this tasty salad. We stirred in bits of sautéed ham just before serving, but it's equally good without.
Prepare peas according to package directions; drain and let cool 1 hour.
Whisk together sugar and next 5 ingredients in a large bowl. Add 1/4 cup oil in a slow, steady stream, whisking constantly until smooth. Add cooked field peas, bell pepper, onion, and celery, tossing to coat; cover and chill 8 hours.
Sauté ham in 1 tsp. hot oil in a small skillet over medium-high heat 4 to 5 minutes or until lightly browned. Stir into pea mixture just before serving.