This is a simplified slow cooker version of a dish that I first had in college when I spent a semester abroad in Madrid, Spain. I chose a home-stay and was matched with an old-school Madrileña grandmother who once told me that she missed Franco. She was a widow living on a pension and did her all of her own shopping, cooking, and laundry and, because I signed up for it, mine too. Every day that fall, I came home from class during the two-hour siesta to a kitchen steamy with whatever she had bubbling on the stove. Whatever I learned about Spanish home cooking was purely through observation, but when I came back to the States, I found that I missed the sopa de lentejas so much that I've been playing with this recipe for years.
*Note: The smoked paprika in the chorizo is key. If you can't find it, use another kind of sausage and add a 1½ tablespoon of smoked paprika.
Put the lentils, onions and garlic in the slow cooker. Slice the chorizo into thin rounds and add to the pot. Pour in the stock and sherry. Stir in the bay leaf and pepper.
Cook on low for 5 hours (or high for 3). Slow cooker times may vary, mine is pretty steady.
Spoon into a bowl and top with chopped parsley.