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When I grill asparagus, I break off the tough ends, put it in gallon bag, dump a bit of olive oil in, squish it around to get the spears well coated. Then I add salt and any other spices, and squish it around some more to get an even coating. When ready to grill, get the grill good and hot. put the asparagus in a grill pan with holes, and onto the grill. Stay with it, and just kind of stir fry it on the grill. If done like I do, it comes off the grill cooked, but still has a little snap to it when you bite into it. not burnt, or mushy at all.