Step 1

Heat 1 tablespoon oil in a large cast-iron skillet over medium-high heat. Add beef, cumin, salt and pepper; cook, stirring often to break up the meat, until evenly browned, about 6 minutes. Using a slotted spoon, transfer the beef to a paper-towel-lined plate; do not wipe out the pan. Add 1 tablespoon oil to the drippings in the pan. Add potatoes; cook, stirring occasionally, until the potatoes begin to caramelize and are tender, about 20 minutes. Transfer the potatoes to the plate with the beef.

Step 2

Heat the remaining 1 tablespoon oil in the skillet over medium heat. Add onion, bell pepper and poblano; cook, stirring occasionally, until tender, about 6 minutes. Add garlic; cook, stirring often, until aromatic, about 1 minute. Add kale and tomatoes; cook, stirring often, until the kale is wilted and the tomatoes are heated through, about 3 minutes. Stir in the beef and potatoes. Sprinkle with scallions, if desired.