2/3 hours on 90 degrees depending how thickly it's cut.
Silver side from the butchers, cut the fat off and slice.
Raid the cupboard for a random mix of soy/teryaki/Worcester sauce with pepper, chilli, garlic powder (whatever random stuff i decide to add) stick it and beef all in a sandwich bag, mix thoroughly and leave in the fridge over night.
Next day put it in a sieve and get the most of the sauce off, pat dryish with kitchen towel.
Chuck it in the air fryer for a few hours. Always turns out pretty decent, only issue is it doesn't last very long before i eat it