Arrange the spinach leaves on four salad plates. Slice figs in half and arrange on the spinach, cut side up. Sprinkle thinly sliced red onion over the spinach, then sprinkle with the cheese, walnuts, and bacon.
Combine sugar, red wine vinegar, water, cornstarch, and a dash of salt in a saucepan and bring to a simmer. Remove from heat and let cool slightly.