Add 2 Tbsp of olive oil and/or butter to your sauce pan and brown the Italian sausage, remove when finished.
(If you are using shrimp or scallops for a seafood marinara, these do not need to be browned and you will add these for the last 5 minutes of marinara cook time).
When the meat is done, add another Tbsp of olive oil or butter and cook the onions for 10-15 minutes until they are soft and browned on the edges.
If using dried herbs, add them to the onions about half way through (if using fresh herbs, wait to add these for the last couple of minutes of cook time).
Add the garlic to the onion for the last 5 minutes
Deglaze the sauce pan with some wine.
Add the tomatoes and bring them to a simmer. If you are making a large batch a mix of crushed and diced tomatoes works very well.
Add the salt, sugar, and pepper to the tomatoes.
Add any additional, optional ingredients to the sauce,
Optional, you can also add a large carrot cut in pieces to the sauce to absorb some acid and release some sugar
Simmer uncovered, stirring regularly, until thickened.
In another pot, cook the pasta in 4 quarts of water to 1# pasta, in an 8 quart or larger pot with 2 Tbsp. salt. Cook extra el dente (2-3 minutes less than the package says) and then stop the pasta from cooking by adding 2 cups cold water. Drain.
Add the pasta back to the pot and add 2-3 ladles of marinara sauce to the pasta and stir over a medium-high heat until thickened.
If using fresh herbs or seafood, add for the last 5-8 minutes of marinara cook time.
Serve pasta on each plate and then add an additional ladle full of sauce on top with some grated cheese.