Add the zucchini, eggplant, pepper, and mushrooms to a bowl. Pour on two tablespoons (60 milliliters) olive oil and add salt and pepper. Toss to coat. Grill on both sides until char marks appear.
Add remaining olive oil to a pan. Add onion and garlic and sauté until fragrant. Add farro and stir to coat in oil. Deglaze with white wine. Once wine has evaporated, slowly add broth, stir and cover. Cook until all the water is absorbed (or until grains are cooked al dente).
Remove farro to a bowl. Chop grilled veggies and mix in farro. Add capers, olives, tomatoes, and lemon juice, and mix in.