Aleppo lentil soup (syria and lebanon)

1 cup split red lentils, washed
6 cups water
1/4 cup flour
1/4 cup lemon juice
salt, to taste
2 tablespoons olive oil
4 cloves garlic, crushed
1/4 cup finely chopped fresh cilantro, leaves only
1 teaspoon cumin
1 pinch cayenne pepper

1. Place the lentils in a pot with 5 cups of the water. Bring to a boil, then lower the heat and simmer for approximately 5 minutes.
2. In the meantime, mix the flour with the remaining water to make a smooth paste. Add to the lentils. Stir in the lemon juice and salt and continue stirring over a high heat until the soup mixture returns to a boil. Lower the heat; then cover and cook for 15 minutes, stirring once in a while.
3. While the mixture is cooking, heat the oil in a frying pan. Add the garlic and the cilantro and fry until the garlic is golden brown. Stir this mixture into the soup. Simmer for a few minutes, then add the cumin and cayenne pepper. Stir and serve hot.