I learned this technique from my friend Nimco De Waal when she taught a class on Somali cuisine at Milk Street and it's been an ace up my sleeve ever since. It takes 4 ingredients, a vessel with a lot of surface area and a tight seal, and the littlest amount of patience. Then, you'll be on your way to sauces, dressings, marinades with an unmistakeable depth of flavor. I use coconut charcoal briquettes for hookahs since they're small, release very little flavor beyond the smoke, and they haven't killed me yet.
Make 2 cups
1 small charcoal briquette
2 cups full-fat greek yogurt
1 healthy layer of half an onion
1 tbsp + 1 tsp canola oil
Ignite the charcoal briquette the way the box says you should. Meanwhile, smear the greek yogurt in an even layer over the entire interior of the bowl. Nestle the onion layer into the yogurt in the center of the bowl and fill with 1 tsp canola oil. Carefully transfer the ignited charcoal briquette into the onion layer and drizzle with the remaining canola oil. Immediately cover the bowl with a heatproof lid or aluminum foil, then let sit 20 minutes. Discard the onion and briquette, being sure to extinguish the briquette. Transfer to an airtight container and store, chilled, for up to 4 days.