Melt the butter in a large skillet over medium high heat. Sprinkle the brown sugar over melted butter and immediately place endive in the skillet, cut-side down. Cook until browned and caramelized, about 5 minutes. Carefully flip endive and cook until just tender about 2 minutes. Divide into two batches if necessary to avoid overcrowding the pan. Remove endive from the skillet and transfer to a platter. Season with salt.
Arrange clementine slices and burrata on the platter. Top with pistachios and mint. Drizzle olive oil evenly over the salad and finish with flaky sea salt.