Mix the linseed with water, leave to absorb for approx. 30 mins.
In a bowl, mix the flour with all the other ingredients up to and including the almonds. Add the soaked linseed to the dry ingredients along with the soya yoghurt, soya milk, lime zest and lime juice, mix well. Transfer the cake mixture to the prepared tin.
Approx. 30 mins. in the centre of an oven preheated to 180°C. Remove the cake from the oven, leave to cool on a rack. Remove the cake from the tin.
Heat the soya milk, coconut oil and sugar in a pan. Mix the flour and matcha, sieve into the pan, stir in and boil for approx. 1 min. while still stirring. Allow the mixture to cool. Transfer the frosting to a piping bag with a serrated nozzle (approx. 9 mm), decorate the cake with the frosting.