Rinse 2 cups white rice under cold water until water runs clear. In a medium saucepan, combine rice with 3 cups water and 1/2 teaspoon salt. Bring to a boil, then reduce heat to low, cover, and simmer for 18 minutes until tender and water is absorbed. Remove from heat and let stand covered for 5 minutes, then fluff with a fork.

While rice cooks, prepare the marinade. In a small bowl, combine 2 tablespoons olive oil, 2 tablespoons fresh grated ginger, 3 minced garlic cloves, juice of 1 lime, 1 teaspoon black pepper, and 1/2 teaspoon salt. Mix well.

Pat the tuna steaks dry with paper towels. Place in a shallow dish and pour marinade over, turning to coat all sides. Let marinate for 10 minutes at room temperature.

Heat 2 tablespoons olive oil in a large skillet over medium-high heat. Add diced bell peppers and sliced onions. Sauté for 5-6 minutes until softened and slightly caramelized. Season with salt and pepper. Transfer to a bowl and set aside.

In the same skillet, add 1 tablespoon olive oil and increase heat to high. Remove tuna from marinade, shaking off excess. Sear tuna steaks for 2-3 minutes per side for medium-rare, or longer if you prefer more well-done. The center should still be pink.

Remove tuna from heat and let rest for 2 minutes, then slice into thick strips against the grain.

To assemble bowls, divide cooked rice among 4 serving bowls. Top each with sautéed peppers and onions, then arrange sliced tuna on top. Drizzle with fresh lime juice and garnish generously with chopped cilantro. Serve immediately with extra lime wedges on the side.