Add balsamic vinegar, honey, and lemon juice to a small pan and bring to a boil over medium heat. Continue to boil for 10-12 minutes or until reduced by about half.
Heat a large, oven-safe skillet over medium-high heat. Add 1/2 tsp of olive oil, if desired. Add vegetables and sauté until tender-crisp, about 5 minutes. Set aside.
Cut flank steak against the grain into approximately 3" wide strips. If each strip is more than about 1/4" thick, use the smooth side of a meat tenderizer to flatten them out. Season with Montreal Steak Seasoning on both sides. Add vegetables across the center of the steak strips, then roll the strips and secure with a toothpick.
Sear roll-ups in pan for about 3-5 minutes per side (seam side first), then place in 350 degree oven to finish cooking for 7-10 minutes. Adjust based on thickness of steak and desired temperature.
Before serving, spoon balsamic reduction over steak roll ups.