2) Meanwhile, heat the oil in a saute pan, add the onions, leeks, thyme, salt and pepper and cook over medium heat for 10 minutes, until the onions are translucent. Add the garlic and cook for 2 more minutes.
3) Add the drained lentils, celery, carrots, chicken stock and tomato puree. Cover and simmer over a low heat for 20 minutes, until the lentils are tender. Add the vinegar and season to taste.
4) Preheat the oven to 230C/Gas mark 8. Meanwhile, heat an oven-proof saute pan over a high heat for 4 minutes. Rub both sides of the salmon fillets with olive oil and season the tops very liberally with salt and pepper.
5) When the pan is very hot, place the salmon fillets seasoning-side down in the pan and cook over medium heat without moving them for 2 minutes, until very browned. Turn the fillets and place the pan in the oven for 5 to 7 minutes, until the salmon is cooked rare.
6) Spoon a mound of lentils on each plate and place a salmon fillet on top. Serve hot.
For the homemade chicken stock:
1) Place all the ingredients in a 16 to 20L stockpot with 7L of water and bring to a boil. Skim the surface, as needed.
2) Simmer uncovered for 4 hours. Strain the entire contents of the pot through a colander, discarding the chicken and vegetables, and chill.
3) Discard the hardened fat, and then pack the stock in litre containers.