In aluminium baking tray on a preheated grill, mix mole and olive oil together. Add the chocolate and cook until it melts, stirring frequently to keep the chocolate from scorching. Set aside and keep warm.
Toss prawns with salt, garlic powder and paprika and grill until pink, 2 to 3 minutes per side. Remove prawns from grill and chop into pieces. Grill jalapenos and onion slices until nicely marked and slightly softened.
Grill tortillas, turning, until they are warm and pliable. Dip each tortilla in the mole sauce to cover completely. Place some prawns in each tortilla, roll up loosely, and set seam down in mole. Sprinkle the top with mozzarella cheese and grill, covered, until cheese melts.
Put 2 or 3 enchiladas on a serving plate, and top with sliced lettuce, grilled onions, tomatoes, and queso fresco. Sprinkle chili de arbol powder over the top, and serve with lime wedges and grilled jalapenos. Eat fast before "la migra" shows up.