Preheat the oven to 400°F.

Pat the pork cubes dry with paper towels. Season them with 1 tablespoon salt and 1 teaspoon black pepper.

Heat the vegetable oil in a large heavy pot or Dutch oven over medium-high heat.

Sear the pork in batches until browned on all sides. Avoid overcrowding the pot so the meat develops a deep golden crust. Transfer the pork to a plate and set aside.

Place the tomatillos, poblano pepper, jalapeño, and onion halves on a parchment-lined baking sheet.

Drizzle with olive oil and season with the remaining 1 tablespoon salt and 1 teaspoon pepper.

Roast for about 30 minutes, until the vegetables are softened and slightly blistered.

Remove from the oven and allow them to cool slightly. Remove the stems and seeds from the poblano and jalapeño.

Transfer the roasted vegetables to a blender. Add the garlic, cilantro, and chicken broth.

Blend until smooth, or pulse lightly if you prefer a slightly chunky, rustic sauce.

Pour the blended sauce into the same pot used for the pork.

Return the seared pork and any collected juices to the pot. Stir well to coat the meat in the sauce.

Reduce heat to medium-low, cover partially, and simmer for about 2½–3 hours, stirring occasionally, until the pork becomes fork-tender and the sauce thickens.

Turn off the heat and stir in the sour cream for a smooth, creamy finish.

Taste and adjust with additional salt or pepper if needed.