Preheat oven to 450°F. Toss rhubarb with sugar in a medium bowl until well coated. Let stand, stirring once or twice, for about 10 minutes. Spread in an even layer on a rimmed baking sheet. Roast until just beginning to soften, about 5 minutes. Let cool for about 10 minutes.
Meanwhile, make the dressing by whisking the vinegar, oil, salt and pepper together in a large bowl. Add greens and toss to coat with the dressing.
Divide the spinach among 4 plates. Top with the rhubarb, strawberries, goat cheese and maple glazed pecans.