Preheat your oven to 190°C (fan) / 375°F / Gas Mark 5. Line a muffin tin with paper cases.
Put the blackberries in a bowl and toss through 1 tbsp flour until they are all coated. Set aside until required.
In a food mixer or large bowl, mix the dairy-free margarine and sugar until soft.
Add the flour, bicarbonate of soda, salt, the zest of the lemon, and finally the vegan yoghurt and vegan milk. Beat until pale and fluffy.
Tip in the blackberries and stir gently.
Spoon the batter into the muffin tins, (I find a spring-action ice cream scoop really handy for this - perfect portion sizes and no mess!). Bang the muffin tray down hard on your work surface to bring all the little bubbles to the top. If you like, you can sprinkle a little demerara sugar or rolled oats over the top of each muffin at this point, for an extra-crunchy top.
Bake in the oven for 25-30 minutes, until an inserted knife or skewer comes out clean.