PLACE soy sauce, ginger, sugar, sesame oil and red pepper flakes in a small bowl. Whisk to dissolve sugar. Pour into a resealable bag; add meat. Seal and use your hands to distribute the marinade with the meat. Refrigerate for 1 hour or overnight.
PREPARE pasta according to package directions.
HEAT vegetable oil in a large skillet over medium-high heat. Remove meat from marinade; discard marinade. Add to skillet in a single layer; cook for 1 to 2 minutes. Turn over; cook for 1 to 2 minutes or until cooked through. Remove from heat.
ADD spinach and carrots to hot skillet; stir until vegetables are heated through. Add pasta; mix thoroughly to combine. Serve topped with green onions. Add toasted sesame seeds and gochujang.
