Mix both flours, sugar, baking powder and salt in a large container. Store, covered, up to a couple of weeks.
For the honey berry topping: Put 1 bag of the mixed berries in a medium microwave-safe bowl. Microwave on high, stirring a couple of times, until berries are softened but still cold, about 2 minutes. Stir in the vinegar and 2 tablespoons honey. Add more honey to taste. Refrigerate, covered, up to 2 days. Serve at room temperature.
When you are ready to cook, heat oven to 200 degrees; place a baking sheet with a wire rack set on it in the oven. Let the remaining bag of mixed berries sit on the counter to soften slightly.
For the pancakes: Put stick of butter into a microwave-safe bowl; cover loosely with wax paper. Microwave on high (100 percent power) until melted, about 45 seconds. Stir in the 1/2 cup oil.
Whisk eggs smooth in a large bowl. Whisk in skim milk and 1 cup yogurt until smooth. Whisk in butter-oil mixture. Add dry ingredients; whisk gently just until all dry ingredients are moistened. Do not overmix, or your pancakes will be tough. Gently fold in the contents of the remaining bag of mixed berries.