In a medium bowl, place steak tips with 1/2 of marinade and combine. Set aside.
Pre-heat oven to 400 Fº and lightly oil a rimmed baking sheet.
In a large bowl toss potatoes and onions with 1 teaspoon oil and 1/2 teaspoon salt. Place on rimmed baking sheet and bake for 10 minutes.
To the bowl, add asparagus, peppers, zucchini, 1 teaspoon oil and 1 teaspoon salt and placed on rimmed baking sheet and toss around with onions and potatoes. Continue baking for 10 - 15 minutes, making sure that the potatoes are cooked through. Remove from oven.
Pre-heat broiler on high for at least 5 minutes.
Move the vegetables to each side of the sheet pan. Place marinated steak in the center of the pan, and discard extra vinaigrette from bowl.
Place sheet pan on top rack below the broiler and broil for 5 minutes.
Flip sirloin tips to the other side and continue to broil for another 3 minutes, or until cooked through to your desired temperature. We cooked ours to about 135ºF and let it come up to 145ºF when resting.
Remove from oven and let rest for 5-10 minutes.
Serve hot with extra balsamic vinaigrette.
We recommend buying a high-quality balsamic vinegar, as it truly makes a difference in the flavor of the finished dish.
If the size of your steak tips differs from about 1-1/2" in diameter you may need to adjust the broiling time to get your desired temperature. If they are smaller, broil for less time.