3 oranges
2 garlic cloves, minced
2 tablespoons soy sauce
1 1/2 pounds trimmed boneless sirloin or rib eye, cut into 1/2-inch-thick strips (see Note)
1 tablespoon cornstarch
1 to 2 tablespoons canola oil
6 scallions, green parts only, cut into 1-inch lengths
Into a small bowl, finely grate zest and squeeze juice from 1 orange. Add garlic and soy sauce.
With a sharp paring knife, peel remaining 2 oranges. Slice oranges crosswise 1/2 inch thick, then halve slices; push out, and discard any seeds. Set aside.
In a medium bowl, toss meat with cornstarch until coated. Heat 1 tablespoon oil in a large nonstick skillet over high heat. Working in batches (adding more oil if needed), brown beef on all sides, 3 to 5 minutes; transfer to a plate.
Pour juice mixture into skillet, and boil until syrupy, about 1 minute. Return beef to skillet; add orange slices and scallions. Toss until coated and heated through. Serve hot with white rice.