Preheat your oven to 450°F (230°C). Cut the cauliflower into bite-sized florets and pat them dry with a paper towel. Toss the florets in melted coconut oil until well coated, then spread them evenly on a parchment-lined baking sheet.
Roast the florets in the oven for about 10 minutes. This first roast gives them a light golden color and helps develop texture. Make sure they’re spaced out—overcrowding can cause steaming instead of roasting.
While the cauliflower roasts, whisk together gochujang, honey, soy sauce, and rice vinegar in a bowl until smooth. Once the initial roast is done, transfer the cauliflower to a bowl, pour the sauce over, and toss gently until coated.
Spread the coated florets back on the baking sheet and return them to the oven. Roast for another 15 minutes, flipping halfway through, until the glaze is sticky and caramelized and the edges are crisp.
Remove from the oven and immediately sprinkle sesame seeds and green onions on top. Serve hot while the glaze is still glossy and the cauliflower is perfectly crisp.