Spiced Mushroom Gratin with sumac and onion

Prep everything first: chop the aromatics, measure the sumac and onion elements, and pat the mushroom dry so it colours well.

Warm the olive oil in a large pan over a medium heat and soften the onion and garlic until sweet and translucent, about 5 minutes.

Add the mixed mushrooms and glaze until it takes on colour and the edges catch, 4 to 6 minutes.

Stir in the sumac and the rest of the sumac and onion flavours, letting them cook out for a minute until fragrant.

Add the fennel along with a splash of stock or water, then cook briskly until everything is tender and the sauce clings.