Place all of the ingredients for the dressing into a bowl and whisk until combined. Set aside.Lay out the chard leaves. Cut out the thick stem and stack the leaves. Roll the stack up into a cigar and cut into thin ribbons to “shred†the chard.Combine the chard, apple and pecans in a large mixing bowl. Add in the dressing, saving about two teaspoons. Toss to combine fully and then divide into two plates. Top the plates equally with tuna and drizzle the remaining vinaigrette onto the tuna. Season with cracked pepper.