Heat vegetable oil in a cast iron pan over high heat. Add mushrooms, a pinch of salt, and sear for 4-5 minutes, until golden brown. Add garlic and shallot and cook for 1 minute, until the garlic and shallot are lightly cooked and fragrant.
Add chicken stock, then stir in sambal. Add shrimp and cook through, about 2 minutes on each side. Add bok choy and cook until just lightly wilted, about another 2 minutes.