Add all of the ingredients into the bowl of a food processor fitted with the blade attachment. Blend at high speed until smooth, about two minutes, depending on how powerful your mixer is.
Serve immediately for a more dip-like consistency, or chill and serve cold for use as a spread. This is best after being chilled for a day. It will keep for up to a week in the refrigerator.
To serve, top with extra sumac and lemon thyme.
Notes
* To cook the split peas, soak them for at least 12 hours with a teaspoon of baking soda, rinse, cover them with water, and cook until quite soft. They will take quite a while to cook, so I recommend making a larger batch and freezing some for later use.