1 medium green bell pepper, cored and sliced into strips
8 button mushrooms, sliced
6 ounces wiener sausage, bacon, or 2 vegan Beyond sausages, cut into bite size pieces
3/4 cup ketchup
1/2 cup milk or unsweetened oat milk (vegan)
1 teaspoon granulated sugar
1/4 cup pasta water
Grated parmesan cheese
Bring a large pot of salted water to a boil (add 2 tablespoons salt per 3-4 quarts of water).
Meanwhile, melt the butter in a large pan over medium heat, and add the onion slices. Saute for a few minutes, until the slices are translucent (about 3-4 minutes).
Add the sausages and cook for 3 minutes. Add the bell pepper, mushrooms and cook for 4-5 minutes, until the bell pepper slices are soft but still yielding a little crunch. Check that the sausages are fully cooked (if not, cook for a few more minutes) and transfer the ingredients to a plate. Set aside.
Using the same pan, stir in the ketchup, milk, and sugar. Keep stirring until the sauce begins to bubble.
Return the sausages and veggies to the pan and stir to mix the ingredients. Turn the heat off.
Boil the pasta according to the directions on the package and scoop out 1/4 cup of pasta water just before draining.
Drain the pasta and put it back in the pot. Pour the pasta water, spaghetti sauce, sausages, and veggies over it and use tongs or chopsticks to coat the spaghetti evenly.