Remove the fat and tendons from the goulash, cut the pieces to approx. 2 cm. Mix the ingredients for the marinade and marinate the meat for 2 hours at room temperature. Mix it up every now and then.
Peel the potatoes, cut them into bite-sized pieces and keep them ready in the water. Peel the onions and quarter them lengthways. Halve the quarters diagonally, separate and keep ready covered. Wash the peppers, cut off the stem, cut open on one side, remove the grains and partitions and cut across into pieces approx. 2 cm wide.
Squeeze the garlic cloves. Wash the small, green chilli, cut crosswise into thin slices, leave the grains in place and discard the stem. Wash the fresh lemongrass, remove the hard stalk at the bottom, remove the brown and withered leaves and only use the white to light green parts. Cut this into pieces approx. 8 cm long. Remove the outer, green leaves if necessary. Tap the bottom half of the pieces with the back of the knife. The stems should look oval, but remain intact. Wash the kaffir lime leaves and use them whole.
Put the massaman curry paste together with 5 tablespoons of the coconut milk in a wok and fry a little. Deglaze with the coconut water, add the rest of the coconut milk .. Then add the meat together with the remaining ingredients to the stock and simmer for 80 minutes with the lid on. Stir every now and then so that nothing burns. If the broth thickens too much, dilute it with a little coconut water.
After 80 minutes add the strained potatoes, briefly increase the heat supply and continue to simmer for 10 minutes. Add onion and pepper pieces, again briefly increase the heat supply and simmer for another 10 minutes.
Put the finished beef curry in a serving bowl. Serve with cooked white rice and enjoy.