Bring 1 L water with 1 tsp salt to a rolling boil in a large pot. Add the prepared string beans and blanch for 2–3 minutes until bright green and just tender-crisp.

Shock

Immediately transfer the blanched beans to a bowl of ice water (about 1 L) to stop cooking and preserve color. Leave for 2 minutes, then drain thoroughly and pat dry. Toss with 1 tsp vegetable oil to prevent sticking and set aside.

Belacan Sauce

Prepare belacan

If using a solid block of belacan, toast 1 tbs belacan in a dry skillet over medium heat for 30–60 seconds until fragrant (careful not to burn). Alternatively, you can briefly fry it in oil. Remove and let cool slightly.

Toast aromatics (optional but recommended)

In the same skillet, add 2 tbs vegetable oil and briefly fry 3 cloves garlic (peeled), 1 large shallot (quartered), and 2 bird's eye chilies over medium heat for 30–60 seconds until softened and fragrant but not browned. This mellows raw sharpness.

Pound or pulse sauce

Combine the toasted belacan, fried garlic, shallot, chilies, 1 tbs lime juice, 1 tsp palm sugar, 1 tsp fish sauce, and 1 tbs water in a mortar and pound into a coarse paste, or pulse briefly in a small food processor. Adjust texture to a slightly chunky paste that will coat the beans.

Adjust seasoning

Taste the belacan sauce and adjust balance with extra lime juice for acidity, palm sugar for sweetness, or fish sauce for saltiness. If the paste is too thick, add up to 1–2 tsp water to loosen.

Finish and Serve

Combine beans and sauce

Place the drained, tossed string beans in a large bowl. Spoon the belacan sauce over the beans and toss thoroughly to coat all pieces. Use tongs or two spoons to mix gently so beans remain crisp.

Garnish and serve

Transfer to a serving plate. Sprinkle 2 tbs coarsely chopped toasted peanuts and 1 tbs chopped fresh cilantro on top if using. Serve warm or at room temperature as a side dish with rice.