Preheat oven to 425* F
Lay cauliflower steaks and veggies onto a sheet pan. Sprinkle the potatoes and brussles with ½ teaspoon garlic powder, ½ teaspoon onion powder, ¼ teaspoon salt, freshly ground black pepper and drizzle 3 tablespoons of balsamic vinegar over them.
In a small bowl, melt 4 tablespoons of non dairy butter. Drizzle 1 Tablespoon of the melted butter over the brussles sprouts and potatoes. Toss them with your hand to coat the potatoes and brussles sprouts evenly.
Into the remaining 3 Tablespoons of butter, add lemon juice, the remaining ½ teaspoon of garlic and onion powder, the remaining ¼ teaspoon salt and some freshy ground black pepper. Stir to combine.
Using a brush, coat the cauliflower steaks, top and bottom with all of the garlic butter mixture. Roast on the middle rack of a 425* oven for 50-60 minutes or until everything is brown and tender, stopping after 30 minutes to flip the steaks and stir the potatoes and brussles.
While the cauliflower and veggies are in the oven, make the gremolata. Finely chop the lemon zest, parsley, garlic and capers together and set aside.
When the cauliflower and veggies are done, remove from the oven, plate and immediately sprinkle with gremolata. Serve.