Heat oven to 425ᵒF. Place tenderloin on one side of an aluminum foil-lined baking sheet. Bake 20 minutes.
Meanwhile, combine balsamic vinegar, ½ cup honey, mustard and rosemary in saucepan. Cook over medium-high heat until reduced and thickened, about 20 minutes.
After cooking tenderloin 20 minutes, place onions and peaches on baking sheet. Brush with reduced balsamic vinegar mixture. Continue roasting until internal temperature of pork reaches 150ᵒF.
Remove rosemary sprig from balsamic mixture; whisk in remaining ¼ cup honey and oil. Place in freezer for 5 minutes to thicken.
Remove tenderloin, peaches and onions from oven; let pork rest 10 minutes before slicing.
Place kale and spinach in bowls. Top with thinly sliced tenderloin, peaches, onions, crumbled goat cheese and pecans.
Drizzle with balsamic dressing.