Remove the outer leaves from the lemongrass and chop the soft interior. Cut chillies lengthwise, remove seeds, wash and chop. Peel and chop garlic. Wash lime hot, dry, grate peel. Squeeze lime. Mix everything except 1 tsp lime juice with coconut milk, 5 tbsp soy sauce and 1 tbsp sugar. Dab meat dry and marinate in it for at least 2 hours.
Preheat the oven and baking tray (electric oven: 80 °C/circulating air and gas: not suitable). Take the fillets out of the marinade and dab a little (keep the marinade). Fry the fillets in 2 tbsp. hot oil in a pan for approx. 5 minutes. Season with a little salt, remove from the pan, put the pan aside. Put the meat thermometer into a fillet. Place fillets on a baking tray and cook in a hot oven 1-1 1⁄4 for hours until a core temperature of 60-65 °C (slightly pink to through) is reached.
Peel and wash the carrots, cut them in half lengthwise and slice them. Clean, wash and halve the pointed cabbage and cut off the stalk. Cut cabbage into fine strips. Heat 1 tbsp. oil in a pot. Sauté the carrots in it. Add marinade, bring to the boil, cover and cook for about 5 minutes. Add pointed cabbage and continue cooking for 6-7 minutes.
Bring the frying pan to the boil with 100 ml water, 3 tbsp. soy sauce and maple syrup and reduce slightly. Season with the rest of the lime juice and pepper. Wash coriander and cut coarsely. Season vegetables with soy sauce and pepper. Cut the meat open, arrange with vegetables and sauce. Sprinkle with coriander. Serve with basmati rice.