Wash and dry all produce. Thinly slice scallions, keeping greens and whites separate. Mince or grate garlic. Drain and rinse beans. Core and seed poblanos, then cut into 1/2-inch squares.

Heat a drizzle of oil in a large pan over medium-high heat. Add pork and Mexican spice, breaking up meat into pieces. Cook, stirring occasionally, until crisped at the edges and no longer pink, 4-6 minutes. Season with salt and pepper. Remove from pan and set aside on a plate.

Add a drizzle of oil, scallion whites, poblanos, and garlic to pan. Cook, tossing, until lightly browned and softened, about 5 minutes. Season with salt and pepper.

Stir in stock concentrates, beans, crushed tomatoes, and 1/2 cup water. Bring to a boil, then lower heat. Let simmer until slightly thickened, about 5 minutes. Season with salt and pepper.

Return pork and any drippings to pan. Simmer until saucy and very thick, about 5 minutes longer.

Divide chili between bowls. Sprinkle with cheddar and a dollop of sour cream. Sprinkle with scallion greens and serve.