First things first, preheat your oven to 400°F (200°C). Line a large baking sheet with parchment paper for easy cleanup.
Prep your cauliflower: Wash the head, remove the leaves and stem, and cut it into bite-sized florets. Try to keep them roughly the same size so they cook evenly.
In a large bowl, toss the cauliflower florets with the 2 tbsp of olive oil and 1/2 tsp of salt. Spread them out in a single layer on your prepared baking sheet. Don't overcrowd the pan! If they're too crowded, they'll steam instead of getting crispy. Use two pans if needed.
Roast the cauliflower for about 15-20 minutes. This initial roast is KEY to getting them crispy before the sauce goes on and makes them sticky. You want them starting to soften and maybe get a little golden in spots.
While the cauliflower is roasting, make the magical sauce! In a medium bowl, whisk together the minced garlic, grated ginger, honey or maple syrup, soy sauce, black pepper, gochujang, rice vinegar, and sesame oil. Give it a good stir until everything is well combined and looks like a glossy, delicious glaze.
Once the cauliflower has had its initial roast, take it out of the oven. Carefully transfer the partially roasted florets back into the large bowl you used earlier.
Pour the delicious Korean sauce all over the warm cauliflower. Use a spatula or spoon to gently toss everything together, making sure each floret is nicely coated in that sticky, spicy goodness.
Return the sauced cauliflower to the baking sheet, again spreading it out in a single layer.
Pop it back in the oven for another 10-15 minutes. Keep an eye on it – you want the sauce to caramelize and get sticky, and the edges of the cauliflower to look crispy and maybe a little charred.
While it's finishing up in the oven, thinly slice your green onions.
Once done, remove from the oven. Garnish immediately with the sliced green onions and toasted sesame seeds.
Serve hot and watch them disappear! Seriously, they are so good right out of the oven.