Preheat air fryer to 400°F. Toss cauliflower florets with olive oil and air fry in a single layer until golden and crisp on the edges, about 10–12 minutes.

In a heavy-bottomed pot over medium heat, add a drizzle of olive oil until shimmering. Add diced onion, season with salt, and cook until translucent, about 3 minutes.

Stir in Thai red curry paste and lemon zest. Cook for 30 seconds to bloom the spices.

Increase heat to medium-high and add white wine. Stir frequently, cooking until the wine is mostly evaporated.

Add roasted cauliflower, vegetable broth, coconut milk, and sugar. Bring to a boil, then reduce to a simmer. Cook uncovered for 10 minutes.

Remove from heat. Transfer half the soup to a blender and blend until smooth. Return blended soup to the pot and stir to combine.

Season to taste with rice vinegar, salt, and black pepper.

Ladle into bowls and garnish with chopped chives.