Preheat the oven to 180°C.
Cut the orange, lemon and beet into thin slices. Line a baking sheet with baking paper, then place one of the salmon fillets in the baking tray, covered with the slices and 1or2 bay leaves.
Season with salt and pepper, then cover with the other salmon fillet.
Tie the sandwiched salmon with a piece of heat-resistant string.
Tuck a few lemon slices and a couple of bay leaves under the string, on top of the top salmon.
Season the top salmon with salt and pepper.
Bake in a preheated oven at 180°C for 25 minutes.
Serve warm.