Stuffed Tomatoes with Golden Crumb Topping

Name: Stuffed Tomatoes with Golden Crumb Topping
Ingredients: 4 ounces 90%-lean ground beef, or 93%-lean ground turkey; 1 cup cooked brown rice, or 1/2 cup instant brown rice; 4 large ripe but firm tomatoes, (about 8 ounces each); ½ teaspoon kosher salt, divided; Freshly ground pepper, to taste; ¼ cup minced red onion; ½ cup grated Parmigiano-Reggiano cheese, divided; 1 tablespoon minced flat-leaf parsley; 1/2 cup petite green peas, (cooked, if fresh; thawed, but not cooked, if frozen); 2 tablespoons extra-virgin olive oil; 1 small clove garlic, minced; 1 cup breadcrumbs, made from day-old whole-wheat bread (see Tip)