1. If using hijiki, soak it in about half a cup of water. It will soften and expand by the time it’s ready to add to the stir-fry.
2. Transfer the tofu cubes to a paper towel–lined plate or baking sheet and put another couple of paper towels on top; pat occasionally to dry the tofu. Meanwhile, prep the vegetables and ingredients for the sauce. Stir-fries move pretty fast. They are time-sensitive and demand attention, so it is best to have everything prepped before you start to cook.
3. In a wok or slope-sided sauté pan on high heat, heat one tablespoon of the sesame oil and stir-fry the tofu for about three minutes. Move the tofu around continuously until it no longer sticks to the bottom of the pan because it is beginning to release water. Transfer the tofu to a plate or bowl.
4. Heat the remaining two tablespoons sesame oil and stir-fry the carrots for a couple of minutes. Add the green beans, ginger, garlic, and star anise. Continue to stir-fry for a few more minutes. Then add about one-fourth cup water to the pan, cover, lower the heat, and simmer until the carrots and green beans are tender-crisp and brightly colored. Stir in the tofu and the drained hijiki (if using).
5. Whisk together all the ingredients for the sauce. Pour the sauce over the vegetables, turn up the heat, and repeatedly fold the sauce over the vegetables until the sauce thickens. Serve at once, on rice or noodles.
If available, use a colorful mix of orange, yellow, red, purple, and ivory carrots.