Soak mung beans in 2.5 cups water overnight or for at least 4-5 hours.
In the morning after draining water, pour soaked beans onto a plate and look through them. Some beans do not soften. Discard them.
Add soaked beans to a blender. Follow with rest of the ingredients except oil and blend to a fine paste. Add 1.5 cups water to facilitate blending.
Heat a non-stick pan at medium heat. Make sure the pan is hot enough by pouring a drop of water. If water hits the pan with a sizzle and the drop starts jumping, the pan is ready. If not, wait and repeat in a few minutes again. Wipe the water with paper napkin. Pour 1/2 tsp of oil.
Pour about a half cup of mung bean batter into the pan and swirl it around lightly to make a small pancake that's 3-4 inches in diameter. The thickness of the pancake should be between that of a crepe and a flour pancake.
Once the edges become brown, flip and let cook on the other side.
Serve hot. Fold the pancake into half and place a dollop of sour cream and salsa in the middle of the folded pancake. Or eat this pancake with cilantro chutney.