Crumble the fresh yeast into the soy milk. Stir gently and let it sit for about 5 minutes until slightly foamy.
In a large bowl, mix together the spelt flour, sugar, salt, lemon zest, vanilla sugar, and grated tonka bean (if used).
Pour the yeast-soy milk mixture into the dry ingredients. Add the softened vegan butter. Mix everything well and knead until a smooth, elastic dough forms, about 8–10 minutes by hand or 5–6 minutes with a stand mixer.
Place the dough in a lightly greased bowl, cover it with a kitchen towel and let rise in a warm place or the pre-heated oven until doubled in size, usually about 30 to 60 mins.
Once risen, gently punch down the dough and braid it next. Place on a parchment-lined/silicone baking sheet. Cover the shaped dough loosely and let rise again for about 25 more minutes.
Preheat your oven to 180°C (350°F). Gently brush the risen brioche with the soy milk and sugar/syrup mixture, then sprinkle generously with pearl sugar.
Bake in the preheated oven for about 20 minutes, until golden brown. Enjoy!