Preheat the oven to 210°C (410°F) with a rack in the centre. Line a baking sheet with parchment.
Rinse the lentils, cover with 750 ml (3 cups) of water and bring to a boil over high heat. Simmer over medium-low heat until just tender, about 20 minutes, then drain.
Rub the chicken with 1 tsp of the oil, the thyme, oregano, garlic powder and pepper. Cut the peppers into strips and toss with another 1 tsp of oil.
Roast the chicken and peppers on the tray for about 20 minutes, until the chicken reaches 74°C (165°F) in the thickest part.
Rest the chicken for 5 minutes, then slice.
Toss the warm lentils with the roasted peppers, finely sliced red onion, chopped parsley, lemon juice and the rest of the oil.
Serve the lentil salad topped with the sliced chicken.
Tips
Herbs, lemon and pepper replace salt without anyone noticing.