Preheat oven to 180°C (350°F). Line a 6-count muffin tin with cupcake liners - see notes below.
Sift the flour, baking powder, baking soda, and salt into a large mixing bowl, and stir in the sugar and poppy seeds.
In another large bowl or mixing jug, add the egg, okara, and milk and beat until well combined. Add the lemon juice, oil, vanilla, and zest, and mix well.
Pour the wet ingredients into the dry, and mix until just combined, don’t overmix the batter because the muffins will turn out tough.
Spoon the batter into the liners filling them level to the top of the muffin tin.
Bake for 15 – 20 minutes or until a toothpick inserted in the center of a muffin comes out clean.
Remove from the oven, leave the muffins in the tin for 5 minutes, then transfer to a wire rack to cool.