Chinese Sausage and Clam Rice Casserole

Name: Chinese Sausage and Clam Rice Casserole
Ingredients: 4 tablespoons vegetable oil, divided; 1 cup Chinese sausage or salami thinly sliced on a diagonal (about 5 ounces); 3 cups chopped Chinese broccoli (1/2 lb.); 1 1/2 pounds Manila clams; 1/2 cup sake; 3 cups cooked rice, preferably cold, leftover; 1 cup cannellini (white kidney) beans, rinsed, drained; 1/3 cup Pickled Leeks (see recipe); 1/2 cup panko (Japanese breadcrumbs); 1/4 cup sliced scallions; 1 cup white wine or distilled white vinegar; 1/2 cup sugar; 2 medium leeks (white parts only), thinly sliced