1. Preheat the oven to 350°F.
2. In a large saucepan over medium-high heat, warm the olive oil. Add the onion, garlic, jalapeños, cumin, oregano, and red pepper flakes and cook, stirring occasionally, until they soften, about 3 minutes. Add the paprika, lentils, and broth; increase the heat to high; and bring to a boil. Cover, turn down the heat to maintain a simmer, and cook until the lentils are tender, 15 to 20 minutes. Season to taste with salt and pepper.
3. While the lentils are cooking, rub the chicken breasts with olive oil and season with salt and pepper. Place the breasts in a single layer on a small rimmed baking sheet or in a shallow baking dish and roast until the center of the thickest part registers 160°F on an instant-read thermometer, 10 to 12 minutes. Let rest for 5 minutes.
4. Spoon the lentils onto four serving plates or into shallow bowls. Cut the chicken crosswise into slices and lay the slices on top of the lentils. Sprinkle with cilantro and serve right away.
Cook's note: Beluga lentils are so named because they're small, black, and resemble caviar. Look for them in well-stocked grocery stores; if you can't find them, French green lentils are a good substitute, but they will take slightly longer to cook, or an other lentils can work in a pinch.