Soak lentils overnight in water.

Bring soaked lentils to a boil in nonfat chicken broth.

Reduce heat to low and simmer until lentils are tender, about 15 minutes, or longer if not pre-soaked.

While lentils are cooking, thinly slice the yellow onion.

Heat olive oil in a pan over medium heat.

Saute the sliced onions in olive oil for 8 minutes, until golden brown.

Remove sauteed onions from heat and set aside.

Once lentils are tender, add the sauteed onions, dried tarragon, dried oregano, salt, and pepper to the lentil soup.

Cook the lentil soup for 2 minutes, stirring occasionally.

Stir in lemon juice.

Garnish the lentil soup with thin slices of lemon before serving.