In a large heavy pot combine the rice, 2 cups of water and the salt, and bring to a simmer over medium high heat. Lower the heat and continue to simmer, covered, for about 20 minutes, adding about 1 cup of broth after every 10 minutes and stirring occasionally. In total you will use between 2 ½ and 3 cups of the broth, and when it gets to the desired tenderness and consistency remove if from the heat (keep in mind that it will thicken slightly as it cools)
Meanwhile heat the oil in a medium sized skillet. Sauté the garlic and mushrooms for about 8 minutes until the mushrooms are soft and beginning to brown. Add the scallions, ginger, soy sauce, and sugar and sauté for another 2 minutes until everything is fragrant and tender.
Scoop the rice into bowls and top with the mushroom mixture. Serve hot.