In a saucepan over a medium heat, combine the brown sugar, 1 tablespoon olive oil and 2 tablespoons of the syrup from the tinned peaches. Stir to heat through.
Remove the pan from the heat and add the wholegrain mustard, soya sauce, 1 tablespoon olive oil, grated ginger, salt and pepper. Drain the tin of peaches and chop each slice into 3 pieces, then stir into sauce.
Meanwhile, cook the rice as according to the instructions on the packet or in a rice cooker, until tender and fluffy.
In a wok over a medium heat, warm the remaining olive oil and then add the onions and cook and stir until soft and translucent. Then add mushrooms to the wok and cook for 1 minute.
Add the sauce and peaches to the wok, and cook for around 15 to 20 minutes or until sauce is hot and mushrooms are cooked fully.
Remove wok from heat, and stir in fresh coriander and sesame seeds. Serve mushrooms and peaches on bed of rice.