Preheat oven to 400°.
In a large skillet or sauté pan (or roaster, if your skillet isn’t big enough
to hold all the crab), melt the butter and olive oil over medium heat.
Add shallot and garlic and sauté until soft, but not browned.
Add Sambal, parsley and cilantro, reserving a small handful for garnishing.
Add crab, and toss to coat with the sauce. Move skillet to the oven, and roast for 20 minutes, until heated through.
Put crab on a platter, and add the juice of 1–2 limes to the remaining sauce in skillet. Whisk to combine and pour over crab.
Finish with remaining herbs and lime wedges.