Lentil Soup with Swiss Chard and Lemon

I've been so busy with the Mulligan Stew giveaway that this blog has really been neglected!  However, my garden greens are going CRAZY so I am searching out new recipes.  I found this one on a forum, uncredited, so if anyone know where it originally came from, let me know!  I am going to make this for lunches this week.

Lentil Soup with Swiss Chard and Lemon

1 1/2 cups lentils
2 1/2 lbs fresh Swiss Chard
1/2 cup olive oil
3/4 cup chopped onion
3 to 4 garlic cloves
Salt
1 Stalk celery, chopped
3/4 cup lemon juice
1 teaspoon flour
Chopped chives for garnish

Wash and pick over the lentils. Cover them with fresh cold water, and cook, covered, until tender. Wash the Swiss Chard leaves and chop them. Add these and a cup of water to the lentils. Continue cooking until the Swiss chard is done, adding more water if necessary. Heat the olive oil in a skillet and add the chopped onion. Crush the garlic cloves with salt, and add these and the chopped celery to the onion. Continue cooking until the vegetables are tender and blended. Add to the lentil mixture. Mix the lemon juice with the flour and stir it into the soup. Cook gently, stirring occasionally, until the soup is rather thick. Taste for seasoning.