Combine all the ingredients for the pesto in a small food processor, and pulse for a few seconds until well combined. Taste and see if more salt or lemon juice is needed.
Toss the tomatoes in olive oil and season lightly with salt & pepper. Roast in the oven for about 10 minutes, or until tomatoes start to split and release juices.
Brush the baguette slices with olive oil and toast in the oven at 400F for about 3 minutes. Remove from heat.
To assemble the crostini: add about 1/2 - 3/4 teaspoon pesto to each slice of bread. Top each slide with 2-3 burst tomatoes. Drizzle with balsamic glaze. Serve warm immediately.