Lightly grease a grill grate with cooking spray and preheat grill to medium high heat.
In a small bowl, combine the vinegar, shallot, and the pinch of salt, let the shallot pickle while you prepare the pork. In a small bowl combine the preserves and mustard, set aside.
Place the pork pieces between two sheets of plastic wrap and, using a meat pounder or the bottom of a heavy skillet, pound the pork to 1/8 inch thickness.
Season the pork lightly with salt and pepper, grill on one side for 1 1/2 minutes, until grill marks appear. Flip the pork and brush the cooked side with half the apricot mixture. Continue to grill until cooked through, about another 1 1/2 minutes, and the turn and brush the second side with the glaze. Arrange the pork on a large serving platter.
In a large bowl, combine the arugula and tomatoes. Whisk the olive oil into the shallot mixture and toss into the salad. Serve the salad piled on top of the pork.