Sausage and Peppers with Onions {Best Hoagie}

Ingredients (12)

• 2 tablespoons extra virgin olive oil
• 4 Italian sausage links (sweet, hot, or a couple of each)
• 1 large yellow onion, sliced into 1/4-inch half-moons
• 1 green bell pepper, sliced into 3-inch strips
• 1 red bell pepper, sliced into 3-inch strips
• 1 bell pepper of another color (yellow or orange or purple), sliced into 3-inch strips
• Salt, to taste
• 4 garlic cloves, sliced into slivers
• 1/2 cup Marsala or red wine, optional
• 1 (15-ounce) can crushed tomatoes
• 1 tablespoon dried oregano
• 1/2 teaspoon red pepper flakes, optional