Toast the sesame seeds in a large, dry wok or frying pan over a medium heat for 2 mins, tossing the pan, until golden. Tip onto a plate and set aside.
Wipe out the pan, add the sesame oil and return to a high heat. Add the mushrooms and stir-fry for 5-7 mins until golden. Add the ginger, garlic and the white parts of the spring onions. Stir-fry for a further 1 min, then stir in the teriyaki sauce. Bubble for 1-2 mins until heated through, then remove from the heat.
Heat the rice to pack instructions and divide between 2 bowls or plates. Add the carrot and cucumber to the bowl in separate piles. Spoon over the mushrooms and top with the green spring onion tops and the toasted sesame seeds.
