Step 1

In a 12-inch skillet over medium-high, heat the oil until barely smoking. Add the cauliflower and cook, stirring, until charred in spots, 5 to 7 minutes. Transfer to a large plate. Let the skillet cool; add the sugar and 3 tablespoons coconut water; stir. Cook over medium-high, occasionally swirling the pan, until the caramel is mahogany in color, 4 to 6 minutes.

Step 2

Off heat, add the fish sauce and another 2 tablespoons coconut water. Cook over medium, stirring, until any hardened bits dissolve. Add the scallion whites, garlic, ginger, half the chili and ½ teaspoon pepper; cook, stirring, for 30 to 60 seconds. Stir in the mushrooms and a pinch of salt; cook over medium-high until the mushrooms release some liquid, 1 to 2 minutes.

Step 3

Stir in the remaining 4 tablespoons coconut water and the cauliflower. Bring to a simmer, then cover, reduce to medium and cook, stirring, until tender, about 15 minutes. Let stand, covered, off heat 5 minutes. Stir in half the peanuts and remaining chili. Taste and season with more fish sauce and pepper. Sprinkle with the remaining peanuts and scallion greens.