Squeeze 1 orange, peel the others, remove the white skin and fillet. Mix the orange juice with the olive oil, pepper and salt. Cut the fennel into very thin slices and place in the orange juice mixture for 10 minutes. Arrange the orange fillets on 4 plates, top with the onion rings and the fennel. Add the smoked salmon and pour some orange juice sauce over it. Garnish with the olives and chives. A fresh baguette tastes good with it.