- 3 pound boneless pork shoulder (Boston butt), cut into 2″ pieces
- 1 tablespoon ground coriander
- 10 garlic cloves, finely chopped, divided
- 1 tablespoon kosher salt, plus more
- Freshly ground black pepper
- 1/2 cup raw shelled pumpkin seeds
- 6 dried New Mexico or guajillo chiles
- 2 chiles de árbol or 1/2 teaspoon crushed red pepper flakes
- 2 large yellow onions, cut into 1/8″-thick wedges, divided
- 2 tablespoons olive oil
- 4 sprigs oregano
- 1 lb winter squash (pumpkin-type like butternut, acorn, kabocha), peeled, seeds removed, cut into 1″ pieces
- 1 delicata squash, seeds removed, cut into 1/2″-thick slices
- 1/2 small red onion, thinly sliced
- 1/4 cup fresh lime juice
- Cilantro sprigs (for serving)
- Combine pork, coriander, half of garlic, and 1 tablespoon salt in a large bowl; season with pepper and toss. Cover; chill at least 4 hours.
- Preheat oven to 350°F. Toast pumpkin seeds on a rimmed baking sheet, tossing occasionally, until golden, about 5 minutes; set aside.
- Toast chiles on clean baking sheet until slightly darkened, about 5 minutes. Let cool slightly, then remove stems, and seeds, if you prefer less heat. Place chiles, half of yellow onion, remaining garlic, and 1 cup hot water in a blender; let sit 10 minutes to soften chiles. Blend until smooth; set chile purée aside.
- Heat oil in a large Dutch oven over medium-high heat. Working in batches, cook pork, turning occasionally, until browned, 8–10 minutes; transfer to a plate.
- Pour off fat from pot. Cook chile purée in pot over medium-high heat, stirring occasionally, until reduced by half, 8–10 minutes. Add pork, oregano, remaining yellow onion, and 10 cups water to pot; season with salt and pepper. Bring to a boil, reduce heat, and simmer, partially covered, skimming occasionally, until pork is very tender, 3–3 1/2 hours.
- Add squash to stew and cook, uncovered, until pork is falling apart and squash is soft, 30–35 minutes; season with salt and pepper.
- Toss red onion and lime juice in a small bowl; let sit, tossing occasionally, 30 minutes.
- Serve stew with red onion, cilantro, and reserved pumpkin seeds.
DO AHEAD: Pork can be marinated 2 days ahead; keep chilled. Stew can be made 3 days ahead; let cool, then cover and chill.