1. Place shrimp paste, shallots and garlic in a mini food processor (or mortar and pestle) and process to a uniform paste, about 30 seconds on high. You may need to add some neutral oil, a teaspoon at a time, to bring it together into a paste.

2. Bring a large pot of lightly salted water to a boil over high heat. Add the noodles and cook, stirring occasionally to prevent sticking, until the noodles are almost done, still a bit al dente. (Note that cooking time will vary widely by the type of noodle; use the package directions as a loose guide and cook until almost done but still chewy and a bit starchy.) Drain the noodles and toss them in a large bowl with 1 tablespoon neutral oil to prevent sticking.

3. Turn the vent fan on high. Heat a wok over medium-high heat until the air above the wok shimmers, then add the remaining 3 tablespoons oil and fry the shallot paste for 1–2 minutes, breaking it up with a spatula. It will turn toasty brown and smell, well, fishy-fragrant; don’t let it burn. Add the shrimp and stir-fry, stirring constantly, until the shrimp are almost cooked, about 2 minutes. Increase the heat to high, add the cabbage and chile, and stir-fry 1 minute more. Add 4 tablespoons kecap manis, the soy sauce, sambal (if desired) and noodles; stir-fry, constantly tossing, until noodles are evenly brown and glossy from the kecap manis, 1–2 minutes. Remove to a serving platter, drizzle with the remaining 1 tablespoon kecap manis and garnish with scallions. Serve immediately.