2. Put olive oil in a 12-inch skillet over medium-high heat. Saute the tofu cubes quickly in oil, for 2 or 3 minutes, stirring only once or twice. Remove with a slotted spoon.
3. Drain hijiki, and put in skillet; stir once, then add carrots and shiitakes. Stir again; add tofu and peas, stock, and mirin and soy sauce. Stir, turn heat to medium-low, and cook, stirring occasionally, until carrots are tender, about 10 minutes. Mixture should be thick, not soupy. Taste, add more soy sauce or salt if necessary, and serve.