Meatballs:1 slice white sandwich bread, torn into small pieces
8 ounces 20-percent-fat ground beef (about 8 ounces)
2 sweet mild Italian sausages, casings removed
1 tablespoon chopped fresh flat-leaf parsley
1/4 teaspoon kosher salt
1/4 teaspoon freshly ground black pepper
Hearty Meatball Stew:
1 tablespoon all-purpose flour
4 tablespoons extra-virgin olive oil
1 small onion, sliced (about 1 cup)
1 large red bell pepper, cored, seeded and cut into 1/2-inch strips
1/2 teaspoon kosher salt
1/2 teaspoon freshly ground black pepper
1/2 pound large white mushrooms, quartered
One 8 to 10-ounce russet potato, peeled, halved lengthwise and sliced into 1/3-inch slices
4 ounces green beans, trimmed, cut into 1-inch-long pieces
One 15-ounce can diced tomatoes, drained
1/4 teaspoon dried crushed red pepper flakes
1 1/2 cups chicken broth
For the meatballs: Place the bread and 3 tablespoons water into a medium bowl. Mash to a paste with a spatula. Add the beef, sausage, egg, parsley, salt and pepper. Blend the mixture thoroughly with your hands or a flexible spatula. Form the mixture into 10 to 16 meatballs. Arrange the meatballs on a parchment paper-lined baking sheet until ready to use.
For the hearty meatball stew: Sprinkle the meatballs with the flour and turn to coat with any flour still left. Heat a large heavy nonstick skillet over medium heat for 1 minute. Add 2 tablespoons of the olive oil. Drop the meatballs into the skillet, spaced apart. Cook until the bottoms are set and brown, about 2 minutes. Using a flexible thin spatula, turn each meatball onto an uncooked side and cook until the bottoms are set and brown, about 2 minutes longer. Turn and cook a third side, until set and brown, about another 2 minutes, so the meatballs are browned and set all over. Transfer the meatballs to a large plate.
Heat the remaining 2 tablespoons oil in the same skillet over medium-high heat. Add the onions, peppers, 1/4 teaspoon of the salt and 1/4 teaspoon of the pepper. Cook until soft, 4 minutes. Add the mushrooms and the remaining salt and pepper. Cook, stirring occasionally, until the mushrooms have softened, about 5 minutes. Add the potatoes, beans, tomatoes, red pepper flakes and broth and top with the meatballs. Bring the mixture to a boil. Reduce the heat to a simmer, cover the pan and cook until the potatoes are tender and the meatballs are cooked through, about 20 minutes.