In 10-inch skillet, heat 2 tablespoons of the oil over medium-high heat. Cook tortilla strips, a few at a time, 1 to 2 minutes, stirring occasionally, until crisp (if necessary, add additional tablespoon oil); drain tortilla strips on paper towels.
In same skillet, cook beef over medium-high heat 2 to 4 minutes, stirring occasionally, until browned. Stir in all remaining ingredients. Reduce heat to medium; simmer 5 minutes or until vegetables are crisp-tender. Stir in tortilla strips.