In a heavy large pot heat the olive oil over medium heat. Add the onion, carrot and green pepper. Saute the veggies in the olive oil until they become tender, do not burn the onion.
Add the water to the pot and the fish. Bring the broth to a boil at which time add the potatoes. Season with salt and pepper to taste.
Cook for an additional 20 minutes until the potatoes are cooked through.
In a small bowl, beat the egg and sour cream. To the small bowl add 1/4 cup of the broth from the pot. Mix it well with the sour cream mixture. Pour the sour cream mixture to the big pot.Stir well and cook for an additional 5 minutes.
Add the dill and the lemon juice. Season with more salt and pepper if needed.