The beauty of Indian cuisine is its variety. The sheer diversity of spices, seasonings, cooking methods, regional distinctions, dishes and component ingredients makes eating and cooking Indian food a novel, exciting experience each time. One ingredient often used in Indian cuisine is urad dal, a black bean with a white interior. Urad dal has an earthy flavour and is a common ingredient in curry. If you're short on urad dal, you can substitute it for other ingredients.
Replace urad dal with black lentils, which are similar in taste, texture, colour and shape.
Use mung beans. Mung beans are a small legume that are easy to cook because they don't require soaking.
Substitute with azuki beans, which are reddish and small like urad dal, and have a similar texture and taste.
Mask the difference in taste between urad dal and your substitution by tweaking spice combinations. Disguise the substitution by adding more of another ingredient (or combination of ingredients) to balance it out.
Use urad dal flour in the absence of beans, if it will work in your recipe. This flour is composed of ground, dried beans.