Create the "Buttermilk": In a medium-sized bowl or a liquid measuring cup (at least 4-cup capacity), pour in the milk and add the apple cider vinegar. Stir them together briefly and set aside for 5 to 10 minutes. During this time, the mixture will thicken and curdle slightly, acting as a tenderizing buttermilk substitute.
Whisk Dry Components: Select a large mixing bowl. Add the whole wheat flour, ground flaxseed meal, baking powder, baking soda, and salt. Use a whisk to combine these dry ingredients thoroughly, ensuring even distribution for consistent rising and flavor.
Prepare Wet Ingredients: To the bowl containing the thickened milk mixture, add the eggs, maple syrup, melted butter, and pure vanilla extract. Whisk these components together until they form a smooth, well-blended liquid.
Form the Batter: Make an indentation in the center of the dry ingredients. Pour the prepared wet ingredient mixture into this well. Using a spatula or a whisk, stir the wet and dry ingredients together only until they are just combined and the flour is moistened. A few small lumps remaining in the batter are acceptable and preferred over overmixing, which can result in less tender pancakes. Let the completed batter rest for 5 to 10 minutes. This allows the flour to hydrate fully and gives the leavening agents a head start, contributing to a fluffier outcome.
Heat the Cooking Surface: If using an electric griddle, preheat it to a temperature between 360°F and 375°F (approximately 182°C to 190°C). For a stovetop griddle or large skillet (preferably heavy-bottomed or non-stick), heat it over medium heat. To check if the surface is ready, sprinkle a few drops of water on it; they should sizzle and evaporate quickly. If your griddle or skillet is not non-stick, lightly coat it with a small amount of additional butter or neutral cooking oil.
Portion and Cook Pancakes: Gently stir the rested batter once more. For each pancake, pour approximately ⅓ cup of batter onto the hot griddle or skillet. Ensure there is enough space between pancakes for them to spread slightly as they cook.
Flip and Complete Cooking: Cook the pancakes on the first side for about 2 to 4 minutes. You’ll know they are ready to flip when bubbles begin to form and pop on the surface, and the edges appear set and slightly matte (about a ½-inch perimeter). Carefully slide a thin spatula underneath each pancake and flip it. Continue to cook on the second side for another 1 to 3 minutes, or until it is golden brown and the pancake is cooked through the center.
Serve Warm: Transfer the cooked pancakes to plates and serve immediately. They are delicious with fresh fruit, yogurt, a sprinkle of nuts, or an additional touch of maple syrup. If cooking in batches, you can keep the finished pancakes warm by placing them in a single layer on a baking sheet in an oven set to 200°F (around 93°C).