Stir in your mushrooms, and continue cooking for 4-5 minutes more, stirring frequently until golden brown. Season with a tiny pinch of sea salt and pepper.
Squeeze in your fresh lemon juice and stir well.
Reduce the heat to a low, and pour in the coconut milk mixture, then simmer until just thickened, about 4 minutes or so.
Quickly add in the fresh spinach and stir until just wilted, just a minute or two.