Preheat broiler to high.
Top bread with cheese. Broil 30 seconds or until cheese melts.
Heat 3/4 teaspoon oil in a small skillet over medium-high. Add mushrooms; sauté 4 minutes or until browned.
Place kale in a bowl; gently squeeze with your hands until slightly wilted. Add remaining 1/4 teaspoon oil, vinegar, salt, and pepper; toss. Top bread with kale mixture and mushrooms.