Preheat a grill to medium high and oil the grates. Microwave the sweet potatoes until just tender, 10 to 12 minutes. Let cool 5 minutes, then slice in half lengthwise.
Meanwhile, whisk 1/4 cup olive oil, the vinegar, capers and a pinch each of salt and pepper in a small bowl. Slice the cauliflower into small pieces. Grate the beets on the large holes of a box grater.
Coat the asparagus and sweet potato halves with the remaining 1 tablespoon olive oil and season with salt and pepper. Grill the asparagus and sweet potatoes, turning, until charred, 3 to 6 minutes for the asparagus and 10 minutes for the sweet potatoes. Roughly chop them separately.
Toss the greens, cauliflower and asparagus with 3 tablespoons of the vinaigrette and a pinch each of salt and pepper in a large bowl. Divide among plates. Top with the grated beets, sweet potatoes, olives and goat cheese. Drizzle with the remaining vinaigrette.