Cook the red lentils according to the instructions on the package. Peel the sweet potato and cut it into small cubes. Add the sweet potato cubes to the red lentils so they are both ready at the same time. The sweet potato cubes are supposed to be very soft (about 10 minutes).
Drain the lentils and the sweet potato and transfer them into a food processor. Add the garlic, lemon juice, and the spices and process until smooth.
Serve with whole wheat bread, tomato, cucumber, radish, and cress. Store the spread in an airtight container in the fridge.