Thinly slice the scallions, keeping white and green parts separate. Peel the ginger with a spoon and then mince or grate along with the garlic. Cut the lime into wedges. Thinly slice the bok choy leaves and stems. Coarsely chop the mint. Seed and mince the jalapeño. Cut the tofu into 1/2-inch cubes.

Heat 1/2 tablespoon oil in a pot over medium heat. Add the garlic, scallion whites, ginger, and as much jalapeño as you dare and cook for 30 seconds, until fragrant. Add the pho concentrate and 4 cups of water. Bring to a boil and then reduce to a simmer for 10 minutes.

Add the tofu, 1/3 of the rice noodles, and bok choy to the broth. Simmer until the noodles are tender, about 4 minutes. Taste and season with salt and pepper.

Serve the pho in bowls and top with mint, scallion greens, and a lime wedge.