Whisk together the olive oil, lime juice, and garlic in a bowl. Rub the tuna steaks with the mixture. Place the steaks in a sealable container and chill in refrigerator 3 hours.
Combine the mango, bell pepper, Spanish onion, green onion, cilantro, and jalapeno pepper in a bowl; stir. Add the lime juice and 1 1/2 teaspoons olive oil and toss to combine. Chill in refrigerator 1 hour.
Stir together the paprika, cayenne pepper, onion powder, salt, pepper, thyme, basil, oregano, and garlic powder in a bowl. Remove the tuna steaks from the refrigerator and gently rinse with water and then dip each side of each steak in the spice mixture to coat.
Heat 2 tablespoons olive oil in a large skillet over medium heat. Gently lay the tuna steaks into the hot oil. Cook the tuna on one side for 3 minutes; remove to a plate. Pour the remaining 2 tablespoons olive oil into the skillet and let it get hot. Lay the tuna with the uncooked side down into the skillet and cook another 3 minutes; remove from heat immediately.
Spoon about 1/2 cup of the mango salsa onto each of 4 plates. Lay the tuna steaks atop the salsa and serve immediately.