In a blender, combine the rinsed red lentils, water, olive oil, salt, and pepper. Blend until smooth.

Let the batter rest for at least 15 minutes. This allows the lentils to absorb more water, resulting in a better crepe texture.

Heat a lightly oiled non-stick pan over medium heat. Pour 1/4 cup of batter onto the hot pan, swirling to spread it into a thin circle.

Cook for about 2-3 minutes on each side, or until golden brown. Repeat with the remaining batter.

While the crepes are cooking, sauté the spinach, mushrooms, and onion in a separate pan until tender.

Fill the crepes with the vegetable mixture, or serve plain with your favorite toppings.