In bowl, mix vinegar, mustard, oil, honey and salt. Add beets, carrots and pumpkin seeds. Toss to coat. Set aside.
Grill burgers on barbecue preheated to medium-high heat for 5 to 6 min. per side or until cooked through and internal temperature reaches 160°F (71°C).
Assemble burger patties on buns. Top with reserved slaw and alfalfa sprouts.