Wash, dry, and peel potatoes. Grate potatoes and onion with a box grater. In a clean kitchen towel, gather potatoes and onions and squeeze to drain excess liquid. Transfer to a medium bowl. (Alternatively, place a strainer over a bowl and wring potatoes and onions until no liquid drips from them. Pour off the liquid in the bowl but leave the starchy, milky paste that has settled on the bottom. Add the potatoes and onions into this bowl.)

Add the flaxseed egg, whole-milled flaxseed, baking powder, salt, and pepper to the potato and onion mixture. Fold together until evenly distributed.

In a large, shallow pan, heat 1 Tablespoon vegetable oil over medium-high heat. Once oil is hot and starts to move around the pan, carefully spoon a heaping tablespoon of potato mixture into the oil and gently press down to form a small pancake shape. Reduce heat to medium.

Let the pancake cook in the hot oil until golden and crispy on the outside (about 4-5 minutes). Flip and repeat on the other side.

Once pancakes are done, transfer them to a plate or tray lined with paper towels or napkins to absorb excess oil. Serve hot.