03
Brush the salmon with the oil and season with salt and pepper. Place the salmon on the grill, skin side down, and grill until golden brown and slightly charred, about 3 minutes.
04While the salmon is cooking, place the watercress and onion in a medium bowl, add the vinegar and oil and salt and pepper and toss to combine. Transfer the salad to a platter, top with the salmon fillet and drizzle each fillet with the mustard sauce.