Heat olive oil in frying pan and saute the diced onion until it's soft and starting to brown lightly, about 5 minutes. Add garlic, smoked paprika, sweet paprika, dried thyme, Vege-Sal, and black pepper and saute 2-3 minutes more, or until spices are fragrant.
Add onion-spice mixture to Crock Pot, then rinse out the frying pan with 1 cup of the stock and add to crock pot along with red lentils, rinsed chickpeas, and rest of stock. Cook on high for 2-3 hours, or until lentils are starting to soften and dissolve into the soup. (I cooked mine for 2 1/2 hours. Cooking time will depend partly on how old the lentils are.).
When lentils are starting to soften, add the 2 cans of diced tomatoes with juice. Cook for 1-2 hours more on high, or until the lentils and chickpeas are both quite soft. Then remove about 1/2 the soup to a bowl (or the large 8-cup measuring cup I had worked perfectly.) Puree the soup you removed using an immersion blender, food processor, or blender. (If you're using a food processor or blender, be very careful with the hot soup, pureeing in batches if necessary.)
Stir the pureed soup back into the soup in the Crock Pot; taste and add more salt or fresh ground black pepper if desired. Let soup cook about 15 minutes more, then serve hot, with sour cream of plain yogurt if desired.