Combine all dressing ingredients with whisk and set aside.
Rinse and scrub baby beets. Trim each end; place in a small saucepan with water to cover and add white vinegar.
Bring to a boil over high heat. Reduce to simmer and cook until tender, about 25-30 minutes.
Drain and cool.
Place spinach in large bowl with onions and mint.
Cut beetsinto quarters and add to salad.
Top with goat cheese and hazelnuts.
Drizzle salad with desired amount of dressing, toss and serve immediately.