Rinse lentils and place in pot. Cover lentils with water and bring to a boil, season water with salt and cook to tender, about 25-30 minutes. Rinse well and drain.
Place saffron threads, stock and zest of 1 lemon in a small pot and heat to low boil. Then reduce heat to low and keep stock warm.
When lentils are done, bring a large pot of water to a boil for the pasta. Season water with salt and cook pasta to al dente.
Meanwhile, heat EVOO, a turn of the pan, over medium heat then melt butter into the oil and add onions, garlic, chili pepper and sweet pepper, then season with salt and pepper and sauté 5 minutes. Add lentils and season with coriander, cumin and adjust salt to taste.