Step 1

Place a rack on bottom third of oven; preheat to 425°. Cut 4 medium sweet potatoes in half lengthwise and transfer to a large rimmed baking sheet. Drizzle with 3 Tbsp. olive oil, season with 1 tsp. kosher salt, and toss to coat. Roast potatoes until very tender all the way through and deeply charred on cut sides, 25–30 minutes. You can check for tenderness by piercing the flesh with a paring knife or cake tester. Using a spatula, release potatoes from pan.

Step 2

Meanwhile, prep your crunchies and lemony yogurt: Coarsely chop ½ cup blanched hazelnuts. (No hazelnuts? Pistachios, walnuts, and pecans all make good substitutes here.) Pile 1½ tsp. fennels seeds and 1½ tsp. cumin seeds on cutting board in a small mound and finely chop with a chef’s knife. Alternatively, break out your mortar and pestle.

Step 3

Cut 2 lemons in half crosswise. Squeeze juice of 2 lemon halves into a small bowl. Add 1 cup whole-milk Greek yogurt and stir to combine. Season with salt.

Step 4

Heat remaining 1 tsp. olive oil in a small skillet over medium. Cook 2 unsqueezed lemon halves (cut sides down), undisturbed, until well caramelized around the edges, about 3 minutes. Transfer lemons to baking sheet with potatoes.

Step 5

Melt 3 Tbsp. butter in same skillet over medium heat. Add hazelnuts and 2 Tbsp. raw sesame seeds and cook, stirring often, until nuts are golden brown, 3–5 minutes. Add fennel, cumin, and ½ tsp. red pepper flakes and cook, stirring, to bloom spices, about 1 minute longer. Remove skillet from heat; season with ½ tsp. salt.

Step 6

Spread lemony yogurt on a platter. Tear potatoes in half and arrange over yogurt. Spoon crunchies and browned butter over potatoes. Arrange charred lemons on platter for squeezing over.