Here is a simple marinara sauce recipe. You can use it on any dish that requires red sauce. It is very versatile, adding whatever herbs you prefer. If you're using it on fish, you can add anchovies, capers, chopped olives, hot pepper flakes.
Here is all you'll need:
1/2 onion, chopped
2-3 TBS olive oil
1-2 cloves of garlic, sliced
1/4 cup leftover wine
2-3 basil leaves to infuse flavor to the sauce
1 large can of crushed tomatoes or puree
Salt and pepper to taste
Place oil in warm pot. Simmer the onions on low heat. Add the garlic and basil leaves. Simmer very slowly till onions and garlic are soft. Add the wine and cook until the smell of wine evaporates.
Add the can of tomatoes. Stir very well. Raise heat to let sauce come to a soft boil. NEVER LET THE SAUCE COOK AT A RAPID BOIL.
Add the salt and pepper. Add torn pieces of fresh basil and stir. (I like to use parsley if it is being used for fish).
Let sauce come to a slow boil and let cook for approximately 45 minutes. If you see that it has thickened, add 1 cup of fresh cold water, stirring to the consistency you prefer. Add water a little at a time.