1 ripe, juicy mango, peeled, pitted, and coarsely chopped
1/4 cup Chardonnay or other dry white wine
Juice of 1/2 orange (about 1/4 cup)
1/2 to 3/4 tsp. minced habanero, Scotch bonnet, or other hot chile (seeds removed)
Make the marinade
In a large, shallow dish, mix the parsley, cilantro, garlic, sherry, olive oil, salt, and pepper. Add the tuna and toss to thoroughly coat, pressing the herbs all over the steaks. Let sit for 30 minutes.
Make the mojo
In a blender purée the mango with the Chardonnay and orange juice until smooth. Stir in the habanero and set aside. (This mojo is served at room temperature or very slightly warmed—don’t boil it.)
Cook the tuna
Light a charcoal or gas grill. When the grill is very hot, remove the tuna from the marinade and season it with salt and pepper. Sear the tuna for 3 to 5 minutes on each side for medium-rare (or more, depending on the thickness of the tuna). Drizzle some mojo on each plate, set the tuna on the mojo, drizzle on a little more mojo, and garnish with cilantro.