0 Preheat the oven to 425°F.
1 Bring a medium pot of salted water to a boil. Add the lentils, reduce the heat to medium-low, and simmer, uncovered, until the lentils are just tender but still have a slight bite, 12 to 15 minutes. Drain, shaking off any excess water.
4 Meanwhile, in a small bowl, whisk together 1 tablespoon of the oil, the cumin, coriander, paprika, 1/2 teaspoon salt, and several grinds of pepper. Brush all over the sweet potatoes, then place cut side down on one half of a baking sheet.
7 Add the lentils to the other half of the baking sheet. Toss with 1 teaspoon oil, 1/2 teaspoon salt, and several grinds of pepper. Spread into an even layer.
9 Roast, tossing the lentils after 15 minutes, until the sweet potatoes are very tender and the lentils are crispy, 25 to 30 minutes.
11 Meanwhile, finely grate the zest of the lemon into a small bowl. Halve the lemon, squeeze in the juice from half, and reserve the other half. Add the feta, mint, 1 teaspoon oil, and several grinds of pepper. Smash with a fork until combined.
14 Juice the remaining lemon half into a separate small bowl. Add the tahini, 2 tablespoons warm water, remaining 1 teaspoon oil, and 1/2 teaspoon salt. Add more warm water until it’s a drizzly consistency.
16 To assemble, flip the sweet potato halves over. Smash the flesh with a fork, leaving the skins intact. Top each half with the feta, lentils, and a drizzle of the tahini. Garnish with more mint.
