Place cabbage in a fine mesh strainer. Very slowly pour boiling water over the cabbage. Rinse with cold water. Drain well, pressing out as much water as possible.
Add cabbage to large bowl. Add carrot, onion, jalapeno, oregano, and vinegar and toss well to combine. I like to put it all in a bowl with a lid and shake it.
Notes
Curtido tastes best after it has marinated for several hours or days, but you can enjoy it fresh if you’d like. Store curtido in a covered container or mason jar for up to 1 week in the fridge.