Preheat the grill to medium-high heat. When the grill is hot, lightly dip a wad of paper towel into cooking oil with tongs, and glide it over the grates to create a slick surface. What you’re doing here is seasoning the grill, much like you would season a cast iron pan. Repeat this step 4-5 times until your grate is slick.
Blend the spices for the seasoning into a small bowl and blend until well-mixed. Lightly brush the mahi-mahi fillets with a bit of olive oil, then place them into a large mixing bowl. Sprinkle the seasoning over the fillets and rub the seasoning over the fillets with your hands to evenly coat.
Place the fillets on the grill, diagonal to the grate slats. Reduce the heat to medium and close the grill, and let the fillets cook for about 2-4 minutes, depending on thickness. Check on the fish by carefully trying to lift the fillet with a spatula. If the fillet doesn't budge, it's not ready—don't rip it off the grill. Let it cook for another 30 seconds and try again. Repeat until the fish releases itself from the grate, then flip your fillet and let it cook for another 2-4 minutes, or until the internal temperature reaches 145º F. )For a full guide on how to easily grill fish, click here.) Grill your corn alongside the fillets turning it every once in a while. Once most of the corn is lightly charred, remove it from the grill.
Cut the corn kernels off of the cobb by carefully sliding a sharp knife vertically down the cob; put the kernels into the mango salsa and set aside.
Transfer the cooked fish fillets to the cutting board and roughly chop them into bite-sized pieces. Place the slaw into the center of the soft tortillas, then top with chopped fish and a few dollops of jalapeño sauce. Garnish with chopped flat-leaf parsley or cilantro, and mow down!