Heat oil in a medium nonstick skillet over medium-high heat. Add shallots, and sauté 2 minutes. Add tomatoes, pepper, and salt; sauté 2 minutes. Remove from heat; stir in tarragon.
Divide cheese evenly among muffin halves. Place muffins on a baking sheet, and broil 1 minute or until cheese melts. Spoon 1/3 cup tomato mixture over each muffin half. Serve immediately.