Position a rack in the upper third of the oven and preheat to 450 degrees . Place the cauliflower on a rimmed baking sheet, drizzle with 1 tablespoon olive oil and toss; arrange in a single layer on one side of the baking sheet. Place the asparagus on the opposite side and toss with 1 tablespoon oil. Season with salt and pepper, scatter the onion on top of the asparagus and roast until golden, about 10 minutes. Let cool, leaving the oven on.
Place the ground almonds in a shallow bowl. Pour 2 tablespoons olive oil onto a plate; coat each goat cheese round with the oil, reserving the extra oil. Gently turn the cheese rounds in the nuts to coat and place on a baking sheet. Bake until lightly toasted, 3 to 4 minutes.
Divide the roasted vegetables and the orange rounds among 4 plates. Drizzle each plate with the reserved oil and 1/2 tablespoon balsamic vinegar. Serve with 2 goat cheese rounds each.