Heat half the canola oil in a large skillet over medium-high heat. Add the bok choy and sliced garlic. Cook, stirring, until wilted, about 4 minutes.
Add 1 ½ cups broth and simmer until reduced by half. Meanwhile, combine the minced garlic, ginger, fish and soy sauces, brown sugar, and sesame oil.
Heat the remaining canola oil in another skillet over high heat. Add the tofu and brown, about 3 minutes per side.
Add the soy mixture and coat the tofu with it. Simmer, uncovered, until the sauce is syrupy, about 4 minutes.
Stir the cornstarch into the reserved broth and add to the bok choy. Stir gently until thickened, about 2 minutes.
Divide the bok choy among 4 plates. Layer the glazed tofu on top.