Pat the beef dry with paper towel and slice thinly against the grain into bite-sized strips. In a bowl combine light soy sauce, oyster sauce, cornstarch, sesame oil and white pepper. Add the sliced beef and toss to coat. Marinate at room temperature for 15–20 minutes (or refrigerate up to 1 hour).

Belacan Sauce Base

Prepare Belacan

If your belacan is in a solid block, lightly toast it by placing the block in a dry skillet over low heat for 20–30 seconds per side until fragrant (this mellows overly pungent notes). Break into a small spoonful or mince finely.

Make the Paste

In a mortar and pestle or small food processor, combine toasted belacan, sliced shallots, minced garlic and chopped chilies. Pound or pulse until a coarse paste forms. Add tamarind and palm sugar and pulse briefly to incorporate. Add 1–2 tablespoons water if the mixture is too stiff to blend.

Cook the Sauce

Heat 1 tablespoon vegetable oil in a wide skillet or wok over medium heat. Add the belacan mixture and fry, stirring, for 2–3 minutes until aromatic and slightly darkened. Add the remaining 1 tablespoon oil and 3 tablespoons water to loosen. Taste and adjust: if too salty, add a pinch more sugar; if too intense, add a little extra water or a squeeze of lime later.

Vegetables & Finish

Prepare Okra

While the sauce is cooking, trim the okra stems and, if desired, slice them lengthwise to reduce slipperiness. Pat okra dry—moist okra steams rather than sears.

Sear Okra

Push the belacan sauce to one side of the pan. Increase heat to medium-high and add the marinated beef in a single layer to the open space (or remove beef briefly and sear okra first if pan is small). Sear the beef for 1–2 minutes without moving to get a quick browning, then stir and combine with the belacan. Add okra and tomato wedges. Stir-fry everything together for 2–3 minutes until beef is just cooked through (internal edges browned) and okra is tender-crisp. Avoid overcooking okra to prevent mushiness.

Combine & Finish

If the pan looks dry, add 1–2 tablespoons water to create a glossy sauce and help briefly steam okra. Taste and adjust seasoning with a squeeze of lime (or calamansi) and more palm sugar or tamarind if needed. Stir in sliced green onions and cilantro just before removing from heat.

Serve

Transfer to a serving plate and serve immediately with steamed rice. Offer extra lime wedges on the side.