Drain the extra firm tofu and press it between paper towels for 15 minutes to remove excess moisture, then cut into 1-inch cubes.
Clean the leeks thoroughly and slice the white and light green parts into thin rounds.
Heat 1 teaspoon of olive oil in a large skillet over medium heat, add the leeks and garlic, and sauté for 3 minutes until softened.
Pour the vegetable broth into the skillet with the leeks, cover, and simmer for 8 minutes until the leeks are tender and the liquid has mostly evaporated.
Remove the leeks from the pan and set aside; wipe the skillet clean and heat the remaining teaspoon of olive oil over medium-high heat.
Toss the tofu cubes with tamari, sea salt, black pepper, and nutritional yeast until evenly coated.
Place the tofu in the hot skillet and sear for 3-4 minutes per side until a golden, crispy crust forms.
Serve the crispy tofu cubes immediately over the bed of warm braised leeks.