Combine all ingredients in a medium saucepan.
Bring to a boil.
Cover and simmer gently for 10 minutes, covered.
Carefully remove the lid, and blend with an immersion blender (or put the mixture into a blender with the center lid removed; cover opening with a towel). Puree until as smooth or as chunky as you like. This formula is a building block, and it's time to play.
Add a splash or two of water if needed.
Return the mixture to the pan, and, over low heat, simmer until the sauce is the texture you desire. Again, you can reduce tightly to a syrupy consistency, or not at all. It can take as long as an hour if you prefer sticky-sweet-syrupy sauces.
Now, look at the sauces chart, look in your cupboard and your fridge, and start playing with herbs, spices, spirits, condiments, what have you.