1First, prepare the quick-pickled red onions: In a small bowl, combine the thinly sliced red onion, rice vinegar, sugar, and a pinch of salt. Stir well and let sit for at least 15 minutes, stirring occasionally.

2Next, make the Gochujang Aioli: In a separate small bowl, whisk together the mayonnaise, gochujang, toasted sesame oil, and garlic powder (if using) until smooth and creamy. Set aside.

3Prepare the kimchi by roughly chopping any very large pieces to ensure it's easy to eat in the sliders. Drain any excess liquid.

4Heat the vegetable oil in a large non-stick pan or griddle over medium-high heat. Add the sliced halloumi cheese and cook for 2-3 minutes per side, until deeply golden brown and slightly crispy.

5While the halloumi cooks, lightly toast the brioche slider buns. This can be done in the same pan, a toaster, or under a broiler, until just golden and warmed through.

6To assemble, spread a generous layer of the prepared gochujang aioli on both the top and bottom halves of each toasted bun.

7On the bottom bun, layer a small amount of baby spinach or shredded lettuce, followed by a perfectly grilled piece of halloumi cheese.

8Top the halloumi with a spoonful of the chopped kimchi and a few slices of the quick-pickled red onion. Garnish with thinly sliced green onions.

9Finally, cap each slider with its top bun and serve immediately to enjoy this delightful fusion of flavors.