Bring 4 cups of water to boil in a medium saucepan over high heat. Add rice and salt. Reduce heat to low, cover and simmer 15 to 20 minutes, or until water is absorbed and rice is tender. Meanwhile, heat an iron skillet or wok over high heat for 1 minute. Add sesame seeds and stir constantly for 2 minutes or until they are golden brown. Remove to a small dish. Add vegetable oil to the pan and heat several seconds, still over high heat. Add Onion and cook, stirring occasionally, until the Onion is beginning to get a little charred, about 7 minutes. Add tofu and stir occasionally for 2 minutes to heat it through.