Combine brine ingredients in a 2 gallon sealable container and stir until salt dissolves. Place pork chops in the brine and refrigerate for at least 2 hours. Remove from brine (discard brine), pat chops dry and rub lightly with olive oil. Heat a grill pan over high heat until smoking. Grill chops about 5 minutes per side until cooked through. Set aside to rest and make mostarda. Combine all ingredients for mostarda in a small bowl and season to taste with salt. Serve chops topped with mostarda, hot or at room temperature.