Rinse lentils and place in a large bowl. Cover with hot water and let soak for 1 hour. If they drink the water, add more hot water.
While lentils are soaking, heat 3 tbsp of oil in a large pot over medium heat. Add onions, garlic, carrots, celery, celery leaves and cook for 5-6 minutes until slightly golden.
Add tomato paste and saute for another minute. Add grated tomatoes and their juice, bring to a simmer and cook for 6 minutes.
Add vegetable broth, bay leaf, season with salt and pepper. Bring liquid to a boil and reduce heat to a low simmer for 5 mins.
Drain lentils and add to the stock. Continue simmering for 10 minutes and add rice. Cook for an additional 10 mins. Turn off burner and cover with lid. Let stand for 5 minutes. Stir in lemon juice and serve topped with parsley and feta.
Finish with a good drizzle of quality olive oil.