Start the water boiling to cook the spaghetti. Get all the veggies cut up and when the water boils for the pasta start making the sauce. (this assumes your pasta cooks for 10 minutes)
Cut up the onion into slices and then into quarters. Cube the eggplant into about 1/4-1/2 cubes. Cook in about 1/4 cup of water or white vegan wine for 6 to 7 minutes or until soft. Add tomatoes cut into cubes and minced garlic. (you can use crushed but I think minced tastes better). Cook for 2-3 more minutes more. Salt and pepper to taste. (I find that I add more salt & pepper at the table since my wife and I disagree as to what salt to taste means) Add 1 cup of the pasta water and cook for 2 minutes more.
When the pasta is just about done (about 1 more minute to go) add it to the sauce and cook for 1-2 minutes. Its now ready to serve.