Drain the pineapple, collect the juice. Cut slices into small cubes. Wash and quarter the tomatoes and remove the seeds. Finely dice the tomatoes. Clean and wash spring onions, also dice finely.
Wash the coriander, shake dry and cut into fine strips, except for something to garnish.
Warm the vinegar and stir with sugar until it has dissolved. Stir in Sambal Oelek and some salt. Mix marinade with pineapple, tomatoes, spring onions and coriander and let it soak for about 30 minutes.
Just before serving, season again with salt, possibly some Sambal Oelek and pineapple juice.
Peel sweet potatoes, cut into thick slices and precook in boiling salted water for about 5 minutes. Drain sweet potatoes and let them cool down. Wash the lime thoroughly and finely grate the peel.
Squeeze 1/2 lime and measure out 1 tablespoon of juice. Mix butter, lime zest, 1 tbsp. juice, some salt and pepper.
Wash the salmon fillet, dab dry and cut into 6-8 slices. Spread a thin layer of oil on the meat side, salt and pepper lightly. Put the salmon with the meat side first on the grill and grill for about 4 minutes, then turn and grill on the skin side also for about 4 minutes.
Besides sweet potatoes lightly oiled, grill for about 5 minutes while turning. Remove salmon from the grill and spread the lime butter on the hot salmon strands. Garnish with coriander. Add grilled sweet potatoes and pineapple-tomato sambal.