Yoghurt tenderises where lemon juice only toughens. Borrowed, with respect, from the tandoor tradition of North India and Pakistan.
Everything except the chicken into a bowl and stir until smooth. Fold the chicken through until every piece is coated. Cover and refrigerate.
Four hours is the minimum for any effect. Overnight is better. Twenty-four hours is the outside limit and past it the texture starts to suffer.
This is not a marinade that works by acid. Yoghurt is only mildly acidic, and its calcium activates enzymes already present in the meat that break down connective tissue slowly and evenly.
A straight lemon-juice marinade does the opposite over the same period — the acid denatures the surface proteins, they contract, and the outside goes chalky while the inside is untouched.
Soak wooden skewers for thirty minutes first, or use metal. Thread the pieces with a few millimetres between them — packed tight, the sides touching each other steam rather than char, and char is the whole point.
A grill, a barbecue, or a heavy pan taken to the point where it is almost smoking. Four to five minutes a side, turned once. You want blackened edges against pale meat, not an even golden brown.
If the marinade is dripping and flaring, that is correct. Scrape the excess off the pieces before they go on if there is a lot of it.
On a warm plate, not covered — covering them will soften the char you just spent ten minutes making. Lemon over at the table.
Too long in the marinade. Past about twenty-four hours the enzymatic breakdown stops being tenderising and starts being degradation — the outer few millimetres turn soft and slightly pasty, and no amount of heat will firm them up again.
Thigh is more tolerant of this than breast, which is one of several reasons this recipe uses thigh.