Peel garlic and ginger and dice finely. Wash 1 orange thoroughly and finely grate the peel. Mix the orange peel with maple syrup, soy sauce, ginger and garlic.
Wash meat, dab dry, cut rind diagonally into strips. Place in a large freezer bag and add marinade. Close the bag and massage the marinade into the meat, turning the bag several times.
Leave to marinate overnight in the refrigerator.
Peel 2 oranges so that the white skin is completely removed and cut into slices. Grease the fat pan with oil and line it with orange slices in the middle. Take the meat out of the freezer bag, let the marinade drip off a little and catch it.
Rub the meat all around with about 2 teaspoons of salt and place the meat side on the orange slices.
Roast in the preheated oven on the 2nd rail from below (electric oven: 175 °C/ circulating air: 150 °C/ gas: see manufacturer) for approx. 2 1/2 hours. Squeeze juice from 2 oranges and measure 150 ml juice. About 1 1/2 hours before the end of the frying time, pour orange juice, remaining meat marinade and 250 ml water for frying.
Peel and clean the carrots and cut them in half lengthwise. Peel onions and cut into slices. About 45 minutes before the end of the frying time, spread carrots and onions around the roast, season with salt and pepper and braise.
Turn the carrots once in a while. Let the finished roast rest in the switched off oven for about 10 minutes. Boiled potatoes taste good with it.