Preheat oven to 375 degrees F (190 degrees C). Line a baking sheet with parchment paper.
Evenly spread out Green Beans (2 cup) and Cherry Tomato (2 cup) on a baking sheet. Drizzle with Olive Oil (1 tablespoon) and toss to coat vegetables. Sprinkle with Salt and Pepper (to taste).
Place in preheated oven and roast for 15 to 20 minutes, until tomatoes begin to split open.
Meanwhile, bring a pot of water (about 4 cups worth) to a boil and then add Farro (1 cup). Cook for 15 to 20 minutes until al dente. Drain and set aside.
While the vegetables are roasting and farro is cooking, start the onion and mushrooms caramelization. Place a cast iron skillet (or any heavy bottom skillet) over medium-high heat and add Olive Oil (1 tablespoon) and Butter (1 tablespoon).
Once the butter is melted, add Yellow Onion (2) and Mushroom (8 ounce) and toss to coat. Let cook, untouched for 5 to 7 minutes. Toss.
Let cook for another 5 to 7 minutes, untouched. At this point, add a pinch of salt and toss.
Remove skillet from heat, add Balsamic Vinegar (2 tablespoon), and toss to coat. Return skillet to heat and continue to cook, tossing occasionally, until onions are browned and broken down, another 10 to 15 minutes.
In a large serving bowl, toss together the beans, cherry tomatoes, onions, mushrooms, and farro. Serve warm.