Rub steaks with Cajun spice; place in resealable plastic bag. Combine 1/2 cup (125 mL) vinaigrette with hot sauce; pour over steaks, seal and refrigerate overnight.
Halve and steam potatoes until fork tender, about 12 min. Let stand 2 to 3 min., then gently toss with 2 tbsp (30 mL) of vinaigrette and green onions. Set aside, keeping warm. Next, cook frozen vegetables according to package directions; season to taste with salt and pepper.
Meanwhile, lightly oil and preheat barbecue (or preheat indoor grill) to medium-high. Remove steaks from marinade. Cook steaks to desired doneness, about 6 to 8 min. per side for medium, depending on thickness. Transfer to a cutting board, lightly cover and let rest 5 to 10 min. Set aside 2 cooked steaks and 2 cups (500 mL) of the potatoes for the Balsamic Steak & Spinach Salad the next night. Spoon remaining 2 tbsp (30 mL) vinaigrette over the steaks as a sauce. Serve with remaining potatoes and vegetables.
Use the leftover steak and potatoes from this recipe to make a hearty Balsamic Steak & Spinach Salad.