Make the rempah:
Cut all the dried chiles into 4 or 5 pieces each with scissors; shake out the seeds. Put the chiles in a small saucepan and cover with water. Bring to a boil and reduce the heat, simmering until the chiles are soft and flexible, about 3 minutes. Drain the chiles, reserving the water. Put the chiles in a blender.
Trim off the root and top section of the lemongrass, leaving a 5- to 6-inch section of bottom stem. Remove the fibrous outer layers until you reach the tender white core. Smash this core with the side of a knife to flatten it slightly. Cut it in half lengthwise and then slice crosswise into thin pieces.
Add the lemongrass, ginger, almonds, shallots, garlic, fish sauce, fresh chiles, and 3 tablespoons of the reserved chile water to the blender. Blend to a smooth purée, adding a few more tablespoons of the chile water, or up to 1/2 cup total if needed, to facilitate blending.
Cook the shrimp in the rempah:
Heat a nonstick wok or stir-fry pan or a large sauté pan over medium heat for 2 minutes. Add the oil and swirl to coat the pan. Scrape the rempah into the pan and fry gently, stirring continuously with a wooden spoon until the oil and rempah are blended and emulsified, about 1 minute. Continue frying, stirring occasionally, until the mixture darkens and thickens to a porridge consistency, 3 to 5 minutes. (If you added extra water to the blender, it may take longer to thicken.) The rempah should separate, with reddish beads of oil on the surface.
Increase the heat to medium-high and add the shrimp and onions. Fry them, tossing and flipping frequently, until the shrimp feel firm to the touch and the onions are crisp-tender, 3 to 5 minutes. Add the tomato, sugar, salt, and lime juice, stirring and cooking just long enough to mix and to heat the tomato wedges without breaking them apart.
Serve with steamed rice.
nutrition information (per serving):
based on four;
sat fat g