Prepare all the ingredients.
Marinate the stingray with salt, rubbing them to evenly distribute the salt evenly. Cover with cling wrap, or transfer to an air tight container and let them rest in the fridge for about 20-30 minutes.
Cut the tomatoes into wedges. Remove the tips from the four angled beans, and cut them into 1.5-2 inches pieces. Remove the stalks and heads of the okra. Pluck the Vietnamese basil leaves and set them all aside.
Chop the ingredients for blending into small pieces: galangal, lemongrass, 1/2 the torch ginger flower, red onion, red chilli and turmeric. Place them all into the blender.
Add the garlic, shallots, chilli paste, shrimp paste (belacan) and 200ml of water to the blender. Blend all the ingredients for about 1 minute, or until a rough asam pedas paste is formed.
Heat the cooking oil in a stainless steel pan over medium heat. Add the asam pedas paste while the oil is still cool, and stir for about 30 seconds, or until just combined.
Add the palm sugar and stir for 10 minutes, or until the sugar has fully melted.
Add the cut lemongrass, onions, and torch ginger flower. Stir continuously for 5 minutes, or until the paste clumps together and sticks lightly to the spatula.
Add the concentrated tamarind water and 600ml of water to the paste, and stir until well-combined. Cover the pan and let it cook for 5 minutes, or until it comes to a rolling boil.
Remove the stingray from the fridge and discard the cling wrap.
After 5 minutes, stir the gravy lightly. Taste and adjust. I added 1/4 tbsp of salt as my shrimp paste was not very salty.
Increase the heat to high, and wait a little until the gravy is bubbling vigorously.
Add the stingray one-by-one, being careful not to move the ones already submerged in the pan. Distribute the okra, four angled beans, tomatoes and 1/2 of the Vietnamese Basil leaves on top of the gravy. Cover the pan and let it boil for 8 minutes.
Open the cover and reduce the heat to medium-low. Stir the gravy a little before tasting to adjust.
Add some cut torch ginger flower and the rest of the Vietnamese Basil Leaves. Pour the gravy over them and switch off the heat.
Cover the pan and let the Asam Pedas Ikan Pari rest for a minimum of 30 minutes.
Dish it out and serve with fluffy white rice.