Choke down the BGE to just under 400F to allow the Mahi to sear nicely but not dry out from too much intense heat. My daughter and I caught two dolphin, a nice bull, and one smaller 'peanut'.
I cleaned the GrillGrates for this treat. They needed it. After soaking in dishsoap and hot water the rails wiped clean and most of the junk wiped away. I made sure the rails were all clean so the Mahi won't stick.
Once the GrillGrates were up to temperature, I used a papertowel to lightly oil the raised rails with canola oil. Olive Oil will burn above 400F)
Preparing the Mahi: Dry filets before preparation. Using very little Olive Oil cover the filet both sides very lightly with olive oil. I then sprinkled Denny Mike's Fintastic over the oiled filet. Ready for the grill.
Place Mahi on the Grill 'FLESH' side down skin or skinned side up) on the GrillGrates. I gave it 5 full minutes and Twisted the filets for cross-hatch sear marks and more surface contact points. The filets lifted right off the rails. LIFT and TWIST the filets- not turning yet. Lid down and wait another 5 minutes. This is where the BIg Green Egg is so clutch. It will hold its temp better than most appliances in the kitchen. I've over-cooked and dried out freshly caught fish before- but the BGE with GrillGrates was terrific and gave me confidence.
Time to turn the filets and cook to the finish. They lifted intact with the Grate Tool and the sear marks were perfect- not crispy black. The presentation side was seared not chared. These were thick filets nearly 2", and I figured they needed at least 5 more minutes. I finally couldn't take it any more and reached in with a fork to see how the fish was doing in the center. Remove filets intact with The GrateTool and straight to the table. Fabulous! We fed 10 with leftovers joining a lunchtime salad.