In a large skillet, heat the olive oil over medium heat. Once hot, add the diced onions and diced red bell peppers. Sauté for about 5 minutes, or until the vegetables are tender and the onions become translucent.
Stir in the minced garlic and cook for another minute, allowing the garlic to become fragrant but not burned.
Next, add the Italian sausage to the skillet. Use your wooden spoon to break it apart as it cooks. Brown the sausage until fully cooked, which should take about 6-8 minutes. Make sure there are no pink bits left.
Sprinkle in the dried oregano, and season with salt and pepper to taste. Stir everything together well.
Pour in the crushed tomatoes, stirring to combine. Bring the mixture to a simmer, allowing the sauce to bubble gently. Let it cook for about 10-15 minutes, stirring occasionally. This will let the flavors meld beautifully.
Once the sauce has thickened slightly, taste and adjust the seasoning if necessary. Serve it over your favorite pasta, or use it as a rich sauce for a homemade pizza. Enjoy the comforting flavors of your Quick and Easy Sausage Marinara Sauce!
