Panang Curry

In a small skillet, toast  chilies, cumin, coriander, and white peppercorns, shaking skillet constantly, until fragrant, about 3 minutes. Transfer to a mortar and pestle and crush into a powder. Add the salt, lemongrass, galangal, lime leaves, cilantro stems, garlic, shallots, shrimp paste, and peanuts. Thinly slice the steak against the grain. Toss with the fish sauce and set aside.  Heat a wok over high. Add 1/2 of the coconut milk and cook until syrupy, about 4 minutes. Whisk in the curry paste and cook for 1 minute. Add palm sugar and lime leaves and continue to cook, stirring, 1 minute. Add the beef and continue to cook, stirring, about 1 minute. Add remaining coconut milk, return  to a simmer and cook, 2 minutes. Remove from heat. Taste and adjust seasoning by adding up to 1/2 tbsp fish sauce. Serve over rice.