Preheat the oven to 350°F. Line an 8x4-inch loaf pan with parchment paper, leaving some overhang on the long sides.
In a large bowl, whisk together the flaxseed meal, baking powder and salt, breaking up any lumps.
In a second bowl, whisk the eggs, water, olive oil and apple cider vinegar for about 1 minute until frothy.
Pour the wet ingredients into the dry ingredients and stir until fully combined. Let the batter rest for 3 minutes to thicken, but no longer, or it becomes hard to spread.
Scrape the batter into the prepared pan, smooth the top and sprinkle with the sesame seeds.
Bake for 45-50 minutes, until the loaf is browned, springs back when pressed and a toothpick comes out clean.
Cool in the pan for 10 minutes, then lift out and cool completely on a wire rack before slicing.