Method:
Preheat oven to 475°F.
Put vinegar, mustard, pear and garlic in a blender with 1/3 cup water and blend until smooth, about 1 minute, to make the dressing. Cut mushrooms into chunks and combine in a large mixing bowl with 1/4 cup of the dressing. Spread mushrooms in a single layer on a rimmed baking sheet. Roast until tender, stirring occasionally, 20 to 30 minutes. Remove from the oven and let cool slightly.
While mushrooms roast, prepare quinoa. In a medium pot, bring 1 3/4 cups water to a boil. Stir in quinoa, cover pot, reduce heat to low and simmer for 15 minutes. Remove pot from heat and set aside, covered, 10 minutes more. Uncover and fluff quinoa with a fork.
Combine mushrooms, quinoa, spinach, green onions, almonds, salt, pepper and 1/2 cup more dressing in a large, wide serving bowl. Stir to mix well. Serve with remaining dressing on the side.