Chilli heads.

1) Buy a jar of jalapeños en escabeche from a commercial brand you like. Herdez ***, La Costeña **, Clemente Jacques ** are a few good ones. Procure a second similar sized empty container and sterilise it.
2) Cut stems off fresh jalapeños, cut fruit width-wise, sauté in olive or vegetable oil over a medium heat, making sure they don’t go mushy (I prefer them slightly crunchy). Let cool.
3) Split jalapeños and commercial pickle between the two containers. Top up with white vinegar. Put containers in fridge for a week and voilá. If you purchased a tin instead of a jar you’ll need to transfer your pickle out of the tin or it will spoil.

You can also sauté carrots and onion with the jalapeño, adding in a bay leaf and maybe a bit of black pepper if you’re sautéing lots.