Mustard-rubbed grilled tri-tip roast with grilled leeks

The night before, score the fat cap with shallow slashes all the way across.

Salt the meat directly by eye, then add whole cumin seeds, dried onion and garlic flakes, paprika and a heavy layer of coarse-grain Dijon mustard.

Rub the spices into the mustard and push the paste into the scored channels. Refrigerate overnight.

Next morning, trim only a tiny sliver from the leek root ends so the layers hold, trim off the dry green tops, and halve lengthwise.

Swish the cut leeks in water so the sand settles, wiping between layers near the top. Dry them.

Coat the leeks gently in olive oil, salt and pepper.

Light charcoal in a chimney starter over paper towel; after ten minutes pour the coals into the grill and top with fresh charcoal.

Insert a thermometer into the thickest part of the roast. Push the coals to one side for a hot and a cool side.

Brown the meat over the hot side, fat side down first, flipping frequently, a little under 10 minutes.

Move the roast to the cool side, thin end furthest from the fire, fat side up. Cover; bottom vents open, top damper half closed, about 400F/200C.

After 10 minutes with the lid on, add more charcoal for the leeks.

At 20 minutes with the lid on, pull the roast at about 125F/52C in the thickest part; about half an hour of cooking in total.

Rest the meat covered with foil.

Clean burned mustard off the grate; grill the leeks with root ends over the hot side, lid on, top damper closed, about five minutes, until softened but still a little crisp. Peel off any over-charred bits.

Slice the tri-tip against the grain.