Preheat oven to 400 degrees F. For sauce, in a small skillet heat oil over medium-low heat. Add garlic, coriander seeds, and crushed red pepper. Cook for 1 to 2 minutes or until fragrant, stirring occasionally. Remove and cool slightly. In a small food processor or blender combine the roasted sweet pepper, the garlic mixture with the oil, and the 1/4 teaspoon salt. Cover and process until smooth.
Cut two 15-inch squares of parchment. Lay one piece of parchment in a 15x10x1-inch baking pan. Place the rhubarb in the center of the paper; sprinkle with sugar. Top with yellow sweet pepper strips and roasted pepper sauce. Top with remaining parchment square. Fold and crease the edges together, working around the parchment to seal. Bake for 15 to 18 minutes or until rhubarb is tender.
Carefully open parchment packet, avoiding steam. Top mixture with mint. Sprinkle with additional salt. To serve, smear cheese over bread and top with warm rhubarb mixture.