Preheat the oven to 375°F. Coat a 9-by-13-inch baking dish with oil.

In a large saucepan, bring 1 ½ cups of water to a boil over high heat. Add the lentils and return to a boil. Reduce the heat to medium-low, cover the saucepan with a lid, and cook for 15 minutes.

Add the couscous and ¼ teaspoon of the salt to the lentils, cover the saucepan once more, and cook, allowing the couscous to absorb all of the remaining liquid and become plump, about 10 minutes. Remove the saucepan from the heat and rest, covered, for 5 minutes longer. Fluff the mixture with a fork.

Add the tomatoes and 2 tablespoons of the reserved tomato oil along with the almonds, feta, green onions, garlic, cumin, thyme, the remaining ¼ teaspoon of salt, and the pepper. Using the fork, stir to combine.

Arrange the bell peppers cut-side up in the prepared baking dish. It’s OK if they look crowded—the peppers will shrink as they roast. Divide the lentil-couscous stuffing between the 8 bell-pepper boats.

Cover the baking dish tightly with foil and bake for 30 minutes. Remove the foil and continue to bake the peppers, uncovered, until tender, 10 to 15 minutes longer.