Italian Sausage and Peppers Sandwich

Name: Italian Sausage and Peppers Sandwich
Ingredients: 1/4 cup (60ml) extra-virgin olive oil, divided; 6 garlic cloves, finely minced (1 ounce; 28g), divided; 2 teaspoons dried Italian seasoning blend (see notes); 1 teaspoon fennel seeds; 1/4 to 1 teaspoon crushed red pepper flakes (see notes); 1 cup (237ml) dry white wine; 2 1/2 cups (591ml) homemade or store-bought low-sodium chicken stock; One 15-ounce (425g) can tomato sauce; 3 medium yellow, red, or green bell peppers (1 pound; 453g each), stemmed, seeded, and cut into 1/4-inch-wide strips (about 5 cups); 2 medium sweet onions (6 ounces; 170g each), thinly sliced (about 3 cups); 1 teaspoon kosher salt; for table salt use half as much by volume; 1/2 teaspoon ground black pepper; 4 sweet or hot Italian sausages (4 ounces; 113g each); Four 8-inch Italian sub rolls, split lengthwise and lightly toasted