Halve and peel onion, then cut into ½-inch pieces. Core tomato and cut into ⅓-inch pieces. Core and seed poblano, then cut into ⅓-inch squares. Drain and rinse beans. Add onion, poblano, Southwest spice, and a drizzle of bacon grease to pan used for bacon over medium-high heat. Cook, tossing, until softened, about 5 minutes.