Begin by patting the tuna steaks dry with a paper towel and season both sides generously with salt and black pepper.
Heat a non-stick skillet over medium-high heat and add 1 tablespoon of olive oil.
When the oil is shimmering, carefully place the tuna steaks in the skillet and sear for about 2-3 minutes per side for a nice crust while keeping the center rare.
Transfer the seared tuna steaks to a plate and cover loosely with foil to keep warm.
In the same skillet, add the remaining 1 tablespoon olive oil and minced garlic. Sauté the garlic for 30 seconds until fragrant.
Add the green beans to the skillet and toss with the garlic. Sauté for about 5-7 minutes until the beans are tender-crisp. Adjust seasoning with a pinch of salt if needed.
While the green beans are cooking, prepare the brown rice if not already cooked. Reheat if necessary to serve warm.
For the tahini drizzle, in a small bowl, whisk together the tahini with a splash of warm water to achieve a smooth, pourable consistency. Season lightly with salt if desired.
Plate the dish by arranging a serving of brown rice alongside a generous portion of garlic green beans, and place a seared tuna steak on top.
Drizzle the tahini sauce over the green beans and rice, and serve immediately to enjoy a flavorful, high-protein meal.