Buttermilk Biscuits with Sausage Gravy

Name: Buttermilk Biscuits with Sausage Gravy
Ingredients: 1 3/4 cups Southern all-purpose flour, such as White Lily, or cake flour (not self-rising), plus more for rolling out; 1/2 cup whole wheat pastry flour; 1 tablespoon baking powder; 1/2 teaspoon fine sea salt; 1/4 teaspoon baking soda; 2 tablespoons cold unsalted butter, cut into bits and chilled; 3/4 to 1 cup lowfat buttermilk; 2 tablespoons canola oil; 1 1/4 pounds lean pork, chicken or turkey sausage, casings removed; Coarse kosher salt and freshly ground black pepper; 1 sweet onion, finely chopped; 2 cups 2-percent or whole milk