Cut a small slit in two tomatoes; insert a garlic clove in each. Place tomatoes and onion in slow cooker. Cut stem off jalapenos; remove seeds if a milder salsa is desired. Place peppers in slow cooker. Cover and cook on high for 2 1/2 to 3 hours or until vegetables are softened (some may brown slightly); cool. In blender, combine tomato mixture parsley and salt . Process until smooth. Refrigerate leftovers. Also freezes well.
I use my hand blender to process, then I can chop it all right in the slow cooker and don't have to transfer it to blender container.