1 pork tenderloin (1 to 1 1/2 pounds), trimmed and cut into 3/4-inch cubes
Neutral cooking oil, such as canola
1 small onion, chopped
1 poblano pepper, seeded and chopped
3 to 4 garlic cloves, peeled and minced
1 heaping tablespoon tomato paste
2 teaspoons ground cumin
1 teaspoon packed brown sugar
1/2 teaspoon ground coriander
1/2 teaspoon ground cinnamon
1/2 teaspoon kosher salt
1 (28-ounce) can whole tomatoes, strained (liquid reserved for another use)
3 cups low-sodium chicken stock
2 cups peeled and cubed pumpkin, butternut squash, or kabocha squash
Kosher salt and pepper, to taste
Cooked white rice, for serving
Pumpkin seeds, for serving (optional)
Pat the cubed pork dry with paper towels and season generously with salt and pepper. Heat two to three tablespoons of oil in a large Dutch oven over medium-high heat until sizzling. Working in batches (do not crowd the pan), cook pork until well-browned, about 1 to 2 minutes per side. Remove with a slotted spoon to a separate bowl and set aside.
Add the onions and peppers to the Dutch oven. Add a pinch of kosher salt and cook, stirring frequently, until the onions begin to turn golden, about 10 minutes. Stir in the garlic, tomato paste, cumin, brown sugar, coriander, cinnamon, and salt, and sauté for about a minute.
Pour in 1 cup of chicken stock and increase heat to high. While the mixture comes to a boil, use a wooden spoon to scrape all the brown bits off the bottom of the pan. Continue boiling until the liquid has reduced to a glaze, and then add the remaining 2 cups of stock, drained tomatoes, and cubed pumpkin or squash.
Bring the mixture to a gentle boil, and then reduce heat and simmer for 20 minutes, until the pumpkin is cooked through. Return the pork to the pot and continue cooking until the pork is cooked through, about 10 minutes more. Taste and adjust seasoning with salt and pepper, as needed.
This dish keeps getting better with time, so make 1 or 2 days in advance if possible.