Homemade Spaghetti sauce

3 tablespoons olive oil
2 cups onion, chopped and divided
1 red pepper, coarsely chopped
2 pounds hamburger (at least 90% lean)
5 cloves garlic, finely chopped
1 12 oz. can tomato paste
1 teaspoon kosher salt
1 teaspoon black pepper
3 teaspoons dried oregano
3 teaspoons dried basil
1 1/2 teaspoons dried thyme
2 14-oz. can Italian-style diced tomatoes
2 28-oz. can crushed tomatoes
1 carton fresh mushrooms (optional)
1 1/2 cups beef stock or beef broth
2 tablespoons brown sugar
2 bay leaves
2 tablespoons balsamic vinegar

Heat olive oil over medium high heat. Add 1/2 of the onions and saute until translucent and slightly browned. Add garlic and stir constantly for 1 minute. Add beef and cook until no red is showing. Drain beef slightly. Blend up the remaining onions and red pepper in a blender or food processor until mostly smooth. Add mixture to the garlic, onions and beef and stir to combine, cooking for another minute. Add tomato paste and spices and cook for 1 minute, stirring until combined. Add tomatoes, beef broth and sugar (and mushrooms, if using). Stir until combined and add the bay leaves. Bring to a boil and then reduce to low and simmer for 1 hour, stirring occasionally. Fifteen minutes before serving, stir in the balsamic vinegar.

NOTE: The sauce will seem watery at first but will reduce to perfection after simmering for an hour. I've let it simmer on the stove for up to three hours before with no problems.

*Freezable Meal: The finished spaghetti sauce freezes very well. I store mine in a freezer-safe container. To serve, I thaw in the refrigerator (usually about one day) and reheat over medium-low heat in a saucepan on the stove.