Some vegetables, such as artichokes, are tricky to cook on the barbeque. By the time you get a good char on the outside, the insides are rubbery or mushy. Or they could be undercooked inside and never get that flavour you want on the outside. Here's the solution: Par cook them first. You'll get the best of both worlds.
Image from pussreboots.
In this case, "par cooking" (strictly, partially cooking) means to lightly cook your veggies until they're close to done. Blanch your veggies in hot water so that they're tender and mostly cooked before you toss them on the grill. You can also grill them first and finish cooking them in the oven once you have the char you want on the outside. Either way, you'll lock in the vegetables' flavour while still being able to add grill them.