– 2 1/2 cups all-purpose flour – 2 1/2 teaspoons baking powder – 1/2 teaspoon salt – 1 cup granulated sugar (may add up to 1/2 cup more if you prefer muffins to be sweeter) – 1/4 cup melted butter, cooled down a bit – 1/4 cup vegetable oil – 1 tablespoon lemon juice – 1 1/4 cup milk – 1 teaspoon vanilla extract – 2 large eggs, room temperature – 2 cups frozen mixed berries, cut up into smaller pieces, measure after cutting the berries (berries do not need to be thawed.)