how to make homemade salsa thicker
1 Stir in the tomato sauce, tomato paste, vinegar, diced tomatoes, and brown sugar. Season with chili powder, Italian seasoning, and salt. Bring to a boil, reduce heat to low, and simmer 1 hour.  Mix the cornstarch and water, and stir into the salsa to thicken. Transfer salsa to sterilized jars, leaving 1/2 inch headroom, and seal. Process jars in a boiling water bath 15 minutes. Store unsealed jars in the refrigerator.