Soak both the lentils in warm water for 1 hour. Drain the water and grind along with the ingredients listed under lentil paste and a little salt. Add just enough water to make a coarse paste.
Microwave or boil the beans with turmeric and a little salt until tender. Drain the water and set aside.
Heat 2tbsp oil in a non-stick pan, add the tempering ingredients and once the mustard seeds start to splutter, add the ground paste and cook on medium-low flame until the mixture starts to dry out and cooks through, about 6-8 minutes. Stir frequently to avoid sticking to the pan.
Add the cooked beans. Cover and cook for 5-7 minutes, stirring occasionally. Sprinkle a little water if the consistency is too dry. Season with salt.