Sour lentil soup

Ingredients:

1 1/2 cups white lentils, picked stones, washed and drained
1/2 kg, 16 oz, Swiss chard, trimmed and roughly chopped
1 head garlic, crushed with a dash of salt
1/2 cup finely chopped fresh coriander
1/2 cup oil or butter
1/2 cup lemon juice
4 cups water
1 teaspoon salt
3 medium potatoes, peeled and diced
1/4 cup finely chopped onions
1 teaspoon ground cumin

Preparation:

Put lentils and water in a pot over high heat, bring to a boil.
Lower heat. Simmer for 25 minutes.
Add Swiss chard and potatoes.
Cook over low heat for 15 minutes.
Fry onions in oil, then add garlic and coriander, fry till fragrant for about 1 minute.
Add garlic mixture, cumin, and lemon juice to lentil mixture.
Cook for 10 minutes. Serve hot.