1. Preheat the oven to 450ºF. Place a pot of water on to boil. Toss diced onion with olive oil (about a tablespoon) on a sheet pan and season with salt. Place in the oven. Roast for about 12 to 15 minutes or until the onion is just beginning to char.
2. Meanwhile, add farro to pot of boiling water with kosher salt. Cook for about 15 minutes - taste a few kernels to determine doneness.
3. Place currants in a small bowl. Moisten with 1 tablespoon boiling water and 1 tablespoon white balsamic vinegar. Set aside. Toast pine nuts in a small dry skillet over medium heat until golden brown - watch them carefully! Set aside.
4. Place the greens in a large mixing bowl. When the onions are finished cooking, scrape them off of the pan into the bowl over the greens. Drain the farro, and add to bowl. Season with a big pinch of kosher salt. Drizzle olive oil over the farro while it's still warm. Start with about 2 tbsp. of olive oil. Splash white balsamic over top, start with about 1 tbsp. and adjust after everything has all been mixed together.
5. Drain the currants and add to the bowl. Add the pine nuts to the bowl and toss to coat. Adjust seasoning to taste.