Watch one
Do one
Teach one
This is how it goes here, If I am doing something, I ask "can you do this?"
If they say,"yes", then they do it, if they say "no", then they join me, I will show them how to do the task, then guide them in doing the task, then come back and inspect the task, advices on how to correct anything that is not correct,
I will take them through each stage of making a recipe, explaining what chemistry should be taking place, and why (caramelising onions), then they get to make one,
well that was what I did do, their cakes, bread, pastry is far better than anything I make,
we have a computer in the kitchen, they just look up what delia says on the subject, then have a look at another couple of recipes, get a feel for the process, they tend to use delia times,
clean before you start, clean up afterwards rule, this is key, or they will never learn how to do anything without using the whole kitchen and everything in it.
silicone oven gloves, oven thermometer, they use a timer on the computer, electronic scales, and lots of tins.
stop buying gack completely, none what so ever , if they want it, let them make it, keep a plentiful supply of raw ingredient,
mine can have a cake in the oven in under 20 mins from coming in from school, I couldn't do that, because I don't need cake that much, they do, so it's self driven.
they will soon learn how to make very tasty gack, (Gack in this house is sugary junk food)
there plenty of chopping an onion tutorials on you tube, there is a you tube clip for everything,
I never go in the kitchen when they are cooking, unless they need a second opinion, or something heavy lifting out of the oven, or a big pan of pasta straining.
I promise you they will get very good at cooking very quickly.
one of the first dishes my DD learnt was a simple moules frites because when we go out to eat she always orders it, so bought the ingredients, she learnt how to do the whole thing, because she wanted to know how to make her favourite dish, it may not be the healthiest, but she then went on to make more interesting things,
ask them what their favourite meal is, do it with them once, then they can do it next time, don't do it for them,
in this house if someone can't do something it's their job until they can, and if you can see a job that needs doing, it's considered rude to wait until you are asked to do it.
mine like to cook that way they control (they think) what we are getting.