In a food processor, combine both chilies, shrimp paste, sugar, and salt. Process until smooth.
Heat oil in a frying pan. Add the paste and cook until fragrant.
Add tomato and cook until it gets wilted. Adjust the seasoning and add lime juice, set aside.
Bring a large pot of water to a boil. Add kangkung and let it boil until it's soft but not mushy. Drain off water and refresh the veggie with fresh cold water to preserve its fresh green color. Wring out excess water.
When ready to serve, scoop the plecing chili sauce over kangkung and serve with roasted peanuts.