Curtido is a type of slaw, commonly used to add crunch and brightness to a variety of rich, slow-cooked Latin American dishes.
Combine the cabbage, carrot, onion, and jalapeños in a large bowl. Sprinkle with salt and toss. Let sit for an hour or so, then drain water. Mix together the vinegar and syrup. Pour over cabbage mixture and stir. Cover and refrigerate for several hours or overnight. Taste before serving and adjust seasonings by adding additional salt or more vinegar.