Remove one handful of dal from water and set aside in a bowl. Strain and rinse remaining lentils then lightly blend in a food processor with the garlic and ginger until the mixture just sticks together and forms a sticky, crunchy lentil paste (the mixture should not be too smooth and wet). In a separate bowl combine the crunchy dal paste with the diced onion, reserved handful of dal, fennel, chilli and mix gently by hand. Add a teaspoon of salt to taste.

Using your hands make small to medium sized balls from the mixture (approx 1½ tbsps) and then flatten them into a cookie shape. Fill a heavy based frypan with sunflower oil and bring to medium heat. There should be enough oil to shallow fry the vadai. Test the temperature of the oil by frying a small amount of batter - if it rises to the surface, the oil is ready for frying. In batches, carefully shallow fry the vadai until they are golden brown and crunchy on the outside and cooked inside, flipping as needed (approx 2½-3 minutes each side).

Place on a plate with paper towel to absorb excess oil. Serve hot or at room temperature with your favourite spicy sauce.