Preheat the oven to 220°C.
Using a mandolin or knife, thinly slice the potatoes and arrange them in an even layer on the grill tray.
Pat the salmon skin dry and place it in a single layer over the sliced potatoes. Season the salmon and potatoes with salt and pepper, and finish with a drizzle of olive oil.
Position the grill tray in the upper tray position and cook for 25 minutes.
While the salmon is cooking, prepare the herb sauce. Combine all the ingredients in a bowl and set it aside until serving.
Once the salmon is cooked, divide the fillets and potatoes among four serving plates. Serve with the herb sauce and lemon cheeks.