Shrimp is cooked in aromatic sambal sauce with distinct lemongrass flavor. Stink beans are usually added to this dish but you can definitely make this dish without them.
Add chili and shallots in a blender and process into a paste. Add a bit of water to help it goes if needed. Skip this step if you use chili paste and just thinly slice the shallots
Preheat skillet/wok with oil. Add in chili and shallots mixture and saute until soft and fragrant. about 2 minutes. Add in lemon grass and tomato. Cook for another minute until it smells really good. Add in the petai (if using) and cook for another 2 minutes or until cooked through. Add in the shrimps and cook until shrimps turn color, about 1 minute
Add in boiled water and lower down the heat and let it simmer for 1-2 minutes
Season with salt and sugar. It should taste slightly sweet, savory, and spicy. Serve immediately