Step 1

Locate one jumbo non-stick muffin pan (for 6 large muffins) or two standard-size non-stick pans (for 14 regular muffins). Arrange oven rack so that the muffins will be in the center of the oven. Preheat to 425 degrees F (218 C).

Step 2

In a large mixing bowl whisk together the dry ingredients.

Step 3

Place the butter in a mug or small bowl and melt it in the microwave. Next, if the milk is cold, microwave it in 15 second intervals, just enough to remove the chill (does not need to be warm). In a medium bowl, combine the milk, lemon juice, vinegar, vanilla, and sugar. Whisk well. Pour the melted butter into the milk mixture, whisking again. Immediately pour wet ingredients into dry, and stir until just combined. Do not overmix. The batter should be thick and fluffy. Fold in the blueberries.

Step 4

Use a measuring cup to fill the muffin cups almost all the way to the top. Again, if using standard-size muffin pans, you'll have enough batter for about 14 muffins. If desired, press 2 or 3 blueberries into the top of each muffin. Sprinkle the tops with sugar.

Step 5

Place pan(s) in oven and immediately reduce temperature to 375 degrees F (190 C). Bake jumbo muffins for 24 to 26 minutes and standard muffins for 21 to 23 minutes. Insert a toothpick into the center of one muffin to test for doneness.

Step 6

Allow muffins to cool in the pan for 10 minutes, then transfer to a cooling rack. TIP: Since the jumbo muffins are heavy and somewhat delicate while still hot, I like to place them top-side-down on the cooling rack.