The key here is to prepare everything before starting as once you begin, there is no stopping the stirring to chop and mince.
Place the dried mushrooms in a cup and a half of hot water and let steep while you prep the rest. Heat the stock in a medium sauce pan, bring to a simmer, but do not boil. Once everything else is ready, pour the dried mushroom water, through a sieve, into the stock. Dice the remaining re-hydrated mushrooms and set aside.
Heat up your risotto pan over medium heat, and then add the oil & butter. Once it is hot, sauté the onion and garlic until the onion is beginning to soften. Stir the rice into the pot and stir to coat the rice. Let it heat up a bit until its nice and shiny, stirring constantly. Do not brown the rice!
Begin to add the hot stock a ladleful at a time, stirring the whole time. Only add the next ladleful when the previous one has been completely absorbed. After about the 3rd ladle full add the fresh mushrooms. Continue to stir, adding stock until about 2 cups of stock are left in the sauce pan. Add the re-hydrated mushrooms and the sun-dried tomatoes. By the time you are done stirring in the last ladleful of stock, not only should you be a bit tired, but the risotto should have a nice creamy consistency, but still have some slight firmness to the rice.