A mixed grill is not one recipe. It is three or four cooks that have to land together. Sausages need 20 minutes, a 6oz steak needs 4, an 8oz gammon needs 8, and a burger sits in the middle. Start the slow things first. Shop mixed grill for the cuts that belong on the same plate.
The order
Oven or a low grill for 6x Pork Sausages - 350g Pack at 200°C, 20 minutes. Ten minutes in, start Rump Steak 2x 6oz or a sirloin 2x in a hot pan, 2 minutes a side, rest. In a second pan, Gammon Steak 2x 8oz 4 minutes a side. If you want a burger on the same plate, it can share the steak pan after the steak is resting, 3 to 4 minutes a side. Keep finished meat on a tray in a 100°C oven so the sausage is not cold when the gammon is done. That 100°C hold is the difference between a mixed grill and a staggered breakfast.
BBQ mixed grill
Two-zone fire. Sausages on the cool side first. Steak over the hot zone when the sausages have 8 minutes left. Gammon over medium. Nothing sits over a flare. Shop sausages and beef steaks if you are building the plate from separate collections rather than the mixed-grill shelf. A mixed grill for two is two sausages each, one 6oz steak to share or a steak each, and one gammon to share. More than that is a platter, not a plate.
What not to mix
Do not put a lamb shank next to a fillet. Do not add a rack of ribs and expect it in 20 minutes. Mixed grill means fast cuts: sausage, steak, gammon, maybe a chop or a burger. Eggs and tomatoes in the steak pan after the meat rests. Leftovers from a mixed grill are a better next-day sandwich than they have any right to be. Shop gammon steaks when the plate specifically needs the ham element. Timing, not a secret rub, is the craft.
Two people, one mixed grill: two sausages each, one steak each or one to share, and a gammon to slice between you. That is already a lot of meat. Adding a burger, a chop and a rack of ribs is a buffet, and something will be cold. Keep the plate to three cooks and it will actually arrive together.
Sausages first, steak, gammon, hold at 100°C, plate together. That is a mixed grill, and it is why the cuts sit in one collection even though they are three different cooks.