I own two square ones that
fit over a burner and can accommodate two servings of protein or four pieces of fresh corn or sliced eggplant.
Not exact matches
I know they have a diffuser of sorts that
fits over electric
burners to reduce the heat... I just prefer gas.
Heat oil in a large Dutch oven or other heavy pot
over medium (if lamb doesn't
fit in the pot you have, set a roasting pan
over two
burners instead).
Prepare grill for high, indirect heat and
fit with grill pan (for a charcoal grill, bank coals on 1 side of grill and put drip pan on empty side; for a gas grill, leave 1
burner turned off and place drip pan
over unlit
burner).