Given the task definition and input, reply with output. In this task, you will be presented with the directions of a recipe separated by "," and have to fill in the "___" which is a step that is missing from the recipe.

In a Dutch oven, over medium to medium-high heat, add the vegetable oil.,Add the onion, carrots, zucchini, and red pepper flakes.,Saute/cook vegetables for 4 minutes; stirring often.,Then add the green bell peppers, and cook for 3 minutes more; stirring often.,Add both jars of the spaghetti sauce, and the canned mushrooms, and stir.,______,Serve sauce over cooked spaghetti, and top with grated Parmesan cheese.,*Note: 10/19/09 Today I made this sauce, but with a few modifications. Instead of adding canned mushrooms, I sauteed 8-ounces of fresh, sliced, mushrooms, in a seperate skillet along with 1-1/2 to 2 tablespoons of butter. I cooked the mushrooms over a medium-high heat for about 6-7 minutes. I also cut the zucchini and bell peppers into 3/4-inch pieces. I sauted the zucchini along with the carrots and onion, for 7 minutes, and after I added the bell peppers, I then added a 3/4 teaspoon of the red pepper flakes, and I sauted the entire vegetables for 6 to 8 minutes more. Finally I added the cooked mushrooms, the 2 jars of pasta sauce, and I threw in a pound of already cooked Italian meatballs, and simmered the sauce with the meatballs, while I cooked the spaghetti. This made a large pot full (to feed more than 6 people), and the sauce was nice and thick.
When sauce starts to come to a boil, within a few minutes, lower heat to a simmer, then cover, and simmer the vegetable/spaghetti sauce for 15 minutes.