Preheat oven to 400℉. Prepare 12 muffin cups by spraying lightly with non stick spray or line with paper liners.
In medium sized bowl, whisk together eggs, yogurt or sour cream, oil, strawberry jam, and vanilla.
In separate bowl, whisk together flour, sugar, baking powder, and salt. Add berries, and lightly stir until berries are coated and dispersed.
Fold wet ingredients into dry ingredients, mixing gently just until combined.
Divide batter into muffin cups. Bake for 18 minutes, or until toothpick inserted in center comes out clean or with crumbs clinging. Cool for 10 minutes before removing from tins. Serve warm or at room temperature.
Any type of plain unsweetened yogurt can be used. Buttermilk or sour cream can be substituted, if desired.
If preferred, use 2 cups whole wheat flour or 2 cups all-purpose flour.
Use all blueberries or all strawberries, or another berry of your choice.