Quick, simple, and delicious, these quesadillas let the clean flavors of mahimahi truly shine. I like a fair amount of heat in my "Mexican" food but if you want to tone it down, just use fewer jalapeños.
Heat a cast-iron skillet or griddle over high heat for 3-4 minutes. Coat the mahimahi with 1 tablespoon of the canola oil and sear skin side down for about 5-6 minutes. Flip and sear for 5-6 more minutes.
Coat the jalapeños with the remaining oil. Add the jalapeños to the pan and cook until softened and charred in spots, about 3-4 minutes. Remove from the pan and let cool. Season with salt and pepper, to taste.
Reduce the heat to low. Once cooled, slice the fish and dice the jalapeños. Season the fish with salt and pepper, to taste. Mix the jalapeños into the cheese. Place one of the tortillas on the pan to warm through, and scatter a quarter of the cheese over one half of the tortilla. Layer half of the fish on top, fold the tortilla in half on top and heat through until the bottom layer of cheese melts. Flip and repeat.
Repeat with the other tortilla and the remaining fillings.