Preheat the oven to 350 degrees. Place the corn tortillas which you have brushed with olive oil on a sheet pan and bake them for 6-7 minutes until lightly brown. Turn them over and cook on the other side for a 2-3 minutes. Remove from the oven and set aside.
While you're prepping ingredients, preheat a grill or broiler. Rub the fish with olive oil. In a small bowl combine ¾ teaspoon salt, black pepper, paprika and cumin. Sprinkle all of the seasoning evenly over the fish. If using an outdoor grill, place the fish on a large sheet of aluminum foil which you have poked all over with holes. The fish will cook all of the way through but it won’t stick to the grill.
Place the fish on the grill and cook it for about 6 minutes. Then, turn the fish over and cook for 3-4 more minutes, depending on the type of fish and its thickness.
While the fish is grilling or broiling, slice the cucumbers and melon into long thin strips with the Y-peeler. And, if you want to be fancy, loosely wrap the slices into rolls or you can just lay them on top of the fish.
Evenly divide the fish among the corn tortillas, cover them with the melon and cucumber and give each one a large dollop of avocado crema and some queso fresco. Finally, sprinkle the cilantro over all of the tacos and garnish them with slices of lime.
You can serve these with some Mango Peach Salsa on the side or any other salsa, preferably one which has some fruit in it for some sweetness.