Preheat oven to 400 degrees.Stir together flour, sugar, baking powder, baking soda and salt. In another bowl, stir together melted butter, sour cream, egg and vanilla.
Add wet ingredients and hazelnuts to dry ingredients and stir until just moistened.Fill lightly buttered muffin cups 3/4 full.Make a well in the center and fill with a 1/4 teaspoon of strawberry jam. Bake until muffins are golden. (Approx. 15 minutes)