Put the tomatoes, bell pepper, cucumber, onion, olive oil, almonds, bread, vinegar, jalapeño, and garlic in a blender; season with salt and pepper. Process until smooth, adding up to ½ cup water if necessary. (Work in batches if not all the ingredients fit in your blender at once.)
Taste and adjust the seasoning. Refrigerate for up to a few hours before serving or serve immediately, garnished with the avocado if desired.