Heat oil in a skillet over medium-high heat. Add onion and garlic, and cook until onion is translucent. Add the bell pepper, and saute until tender. Season with salt, pepper, cumin, oregano and bay leaves. Continue cooking until the mixture looks like a yummy green paste with oil around it. Stir in the tomatoes, if using, and cook stirring until all of the liquid is released. Gradually stir in the tomato sauce simmer until the sauce looks really red. Taste, and adjust seasonings if desired. Remove bay leaves.
Now the sauce is done. You can add it to meat, rice, beans fish or potatoes. Thin the sauce down if necessary with water, wine, beer, or whatever is handy.