In a small skillet, heat 2 tbsp. olive oil, add onion and cook until golden. Add garlic and cook 30 seconds longer. Turn off heat.
Combine tomatoes, basil, goat cheese and onion mixture; mix well. Add salt and pepper to taste.
Cut the baguette into slices about 1/2 inch thick. Brush both sides with olive oil and place on the grill over medium-high heat for about 1 minute, turning once, until toasted and lightly charred around the edges.
Top grilled bread with a few spoonfuls of the tomato mixture.
