Make the crostini. Slice the baguette in ½ inch slices. Brush both sides with a little olive oil and place on a parchment paper lined baking sheet.
Bake for 7 minutes. Remove the tray from the oven, turn the slices over and bake for another 5 minutes or until just slightly crispy. The crostini should still be soft on the inside.
Cut the slices of bacon in half widthwise. Cook the bacon just until most of the fat has rendered but not until it's crispy. You will need it to be pliable so you can wrap it around the prawn. Drain and pat with paper towel to remove much of the fat.
Increase oven temperature to 400°F. Wrap each shelled and deveined prawn in a half-slice of bacon and secure with a wooden toothpick. Place on the same parchment-paper lined baking sheet that you used for the crostini and bake for 5 minutes, just until the prawn has lost its translucent appearance, has turned pink, and the bacon is crispy. For crispier bacon, broil for 3 minutes, watching carefully.
To serve, place each bacon-wrapped prawn on a crostini, spear with the toothpick and top with 2 teaspoons of fresh salsa.