In a small saucepan over high heat, reduce the vinegar to 1/4 cup. In a mixing bowl, combine the vinegar syrup with the mustard, honey, and ancho chile powder and season to taste with salt and pepper. Let rest 30 minutes. Preheat grill. Brush the salmon with the glaze and grill 3 minutes on each side for medium. Serve with the spicy tomato relish. For the Spicy Tomato Relish: Combine all ingredients in a bowl and season with salt and pepper to taste. Serve at room temperature.