Core Tomatoes. Cut A Small Slit In Two Tomatoes; Insert A Garlic Clove Into Each Slit. Place Tomatoes And Onion In A 3-Qt. Slow Cooker. Cut Stem Off Jalapenos; Remove Seeds If A Milder Salsa Is Desired. Place Jalapenos In The 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 A Blender, Combine The Tomato Mixture, Cilantro And Salt If Desired; Cover And Process Until Blended. Refrigerate Leftovers.