Heat the vegetable oil in a large skillet over medium-high heat until shimmering. Reduce the heat to medium and add the shallot and ginger. Add a sprinkle of salt and saute until the shallot is just translucent.
Add the red curry paste to the skillet and saute until it melts and becomes fragrant, about 2 minutes. Stir in the kecap manis, soy sauce, sambal oelek, and palm sugar. Bring the mixture to a boil, then reduce the heat to low. Let cook for 5 minutes.
Remove the skillet from the heat and immediately stir in the peanut butter. Stir until well-integrated. Pour in the coconut milk and, again, stir until well-integrated. Stir in the chili and set the sauce aside to cool completely.
Once cool, transfer the sauce to a bowl and cover. Transfer the sauce to the fridge until ready to serve. Let stand at room temperature for 15 minutes before serving.