How to Make It
Heat a large cast-iron skillet over medium-low. Working in batches, arrange ancho and guajillo chiles in a single layer in skillet; cook, turning once, until lightly toasted, about 30 seconds per batch. Transfer to a large bowl; add 3 1/4 quart warm water, and let stand until chiles are soft and pliable, about 30 minutes. Drain chiles, reserving 5 cups soaking water.
Add peppercorns, cloves, and cinnamon to skillet; toast over medium-low, stirring constantly, until aromatic, about 30 seconds. Transfer mixture to a plate.
Add garlic and onion halves to skillet. Increase heat to medium-high; cook, turning garlic often, until cloves are tender and charred, 12 to 15 minutes. Transfer garlic to plate with spice mixture. Continue cooking onion, turning once, until tender and charred, about 5 more minutes. Transfer to plate with spice mixture and garlic. Peel garlic cloves; discard skins.
Melt 1 tablespoon coconut oil in skillet; add raisins, and cook, stirring constantly, until raisins puff up, about 40 seconds. Stir in oregano and thyme; remove from heat.
Working in batches, process soaked chiles, spice mixture, garlic, onion, raisin mixture, pecans, almonds, tomatoes with juices, sesame seeds, and 4 cups reserved soaking water in a high-speed blender, scraping down sides of blender as necessary to loosen mixture, until mixture is the texture of a thick and coarse tomato sauce, about 1 minute and 15 seconds per batch. Add splashes of reserved soaking liquid as needed to reach desired texture. Pour mixture through a wire-mesh strainer into a large bowl; discard solids.
Melt remaining 2 tablespoons coconut oil in a 12-inch high-sided skillet over medium. Carefully pour in strained mole mixture. (It will splatter.) Cook, stirring often, until warmed through, 7 to 10 minutes. Transfer mole mixture to a large slow cooker. Cook, uncovered, on high, stirring every 30 minutes, until mixture resembles consistency of wet sand, 6 hours and 30 minutes to 7 hours. Remove from heat; stir in brown sugar and salt.
Place turkey broth in a saucepan. Bring to a boil over high; whisk in 2 cups of the mole mixture. Reduce heat to low; simmer, stirring occasionally, until slightly thickened, 20 to 25 minutes. Season to taste with brown sugar and salt. Serve mole sauce over warmed leftover turkey, and garnish with sesame seeds.