Wash the cabbage under cool running water and pat it dry with a clean kitchen towel or paper towels. Moisture on the surface prevents proper caramelization, so make sure it's genuinely dry before moving forward.

Place the cabbage cut-side down on your cutting board and remove the core by making angled cuts around it with your knife. Slice the cabbage into thin ribbons, about 1/4 inch thick, which helps it cook quickly and evenly while maximizing surface area for caramelization.

Cut your onion in half lengthwise, then slice it into thin half-moons about 1/4 inch wide.

Place your large skillet over medium-high heat and let it warm for about one minute. You want the pan hot enough that butter sizzles immediately when added.

Add the butter to your hot skillet and let it melt completely, then add the sliced onion with a pinch of salt. Cook for about 3 to 4 minutes, stirring occasionally, until the onion softens and turns golden at the edges.

Stir in your minced garlic and cook for about 30 seconds until fragrant, but don't let it brown or it will taste bitter.

Add all your sliced cabbage to the skillet along with the kosher salt and black pepper, then stir well to combine with the onion and garlic.

Stir the cabbage occasionally but not constantly, letting it sit for 1 to 2 minutes between stirs so it develops golden, slightly charred edges. Cook for 8 to 10 minutes total until the cabbage is tender but still has a slight bite, and most pieces have some golden-brown color.

Add the apple cider vinegar and soy sauce, stirring well to coat everything evenly. Cook for another 1 to 2 minutes so the flavors meld and any excess liquid reduces slightly.

Taste your sauteed cabbage and add more salt, pepper, or vinegar if needed based on your preferences.