1) Chop tomatoes (finely), removing the hard green bit in the middle. Grate the ginger and measure out the spices. Clean and slice the mushrooms.
2) Put the mushrooms into a wide pan over low heat, and constantly stir until the liquid dissolves.
3) Add all of the other ingredients, and stir and cook over medium heat until the mushrooms and tomatoes are cooked, and all excess water has boiled away.