Dinner Tonight: Warm Fingerling Potato and Tuna Salad Recipe

Name: Dinner Tonight: Warm Fingerling Potato and Tuna Salad Recipe
Ingredients: 1 onion, diced; 1 rib celery, diced; 1 carrot, peeled and diced; 1 bay leaf; 1/2 teaspoon whole black peppercorns; 1 pound fingerling potatoes, scrubbed; 1/2 cup olive oil; 4 tablespoons red wine vinegar; 1 can good-quality tuna in olive oil; 2 tablespoons chopped capers; 1/2 red onion, thinly sliced; 1/2 cup picholine or other green olives, roughly chopped; 1/4 cup chopped parsley; Small handful mizuna or arugula