Preheat the oven to 220 °C (430 °F! yes!) on conventional heat and line a 12-cup muffin tin with paper liners.
Mix wet ingredients: In a separate bowl, combine sugar, soy yogurt, oil, lemon juice, and lemon zest.
Mix dry ingredients: Sift flour, starch, baking powder, and salt over the wet ingredients.
Combine wet and dry ingredients – stir only briefly until just combined. Avoid using a stand mixer; overmixing can make the batter dense. Note: The batter should be thick and slightly fluid – thicker than a regular cake batter, but still easy to stir. Prepare blueberries: Set aside about 36 blueberries (3 per muffin) for the tops. Gently fold in the remaining blueberries and sparkling water. If using frozen blueberries, keep them frozen and toss them in a little flour or starch before folding in.
Fill muffin cups: Use a tablespoon or ice cream scoop to divide the batter evenly. Fill them all the way to the top. This, together with the ingredients and the initial high baking temperature, gives you those beautifully tall muffin tops.
Top muffins: Press the reserved blueberries lightly on top (3 per muffin) and sprinkle some granulated sugar.
Bake: Place in the oven on the middle rack for 7 minutes at 220 °C (430 °F), then reduce the temperature to 180 °C (355 °F) and bake for another 23 minutes, until golden brown and a skewer inserted comes out clean.
Let cool down before you enjoy them.