Line a muffin tray with cases and preheat the oven to 180c.
In a measuring jug, mix together the soy milk and the lemon juice. Set aside to thicken. In a small bowl mix together the psyllium husk powder and the water. Set aside to thicken.
In a medium bowl, mix together the flour, baking powder, baking soda and salt. Set aside.
In the bowl of a stand mixer fitted with the paddle attachment, beat the vegan butter with the sugar, lemon extract and zest until combined. Add the thickened psyllium husk and beat on high speed until combined. Add half of the flour mixture and beat on medium speed to combine. Add half the soy milk mixture and beat to combine. Repeat with the remaining flour, beat and then finish with the remaining soy milk.
Add the poppy seeds and stir with a silicone spatula until well combined. Add the frozen blueberries and stir carefully.
Using a spring loaded scoop or two spoons, fill each cupcake case 3/4 full. Place in the oven and bake for 20-25 minutes. While the muffins bake, make the glaze.