Preheat your oven to 200°C (or 180°C if you're using a fan or convection oven). Line two large trays with baking paper.

Mix the flax seeds with 1 tablespoon of cold water and set aside. It will thicken and become gelatinous. This is your flax 'egg'.

In a large bowl, mix together the margarine, caster sugar, brown sugar and vanilla extract. Add in the flax egg and gently mix it all together.

Add the self-raising flour. Mix until it starts to stick together then use your hands to press it into a ball of dough. If the dough is too dry, add a splash of plant-based milk and if it's too wet, add more flour.

Add the orange zest and press it in using your hands.

Divide the cookie dough into 12 pieces and roll each piece into a ball. Flatten the balls slightly, to create discs that are roughly 1-inch thick.

Place the discs onto your baking tray, leaving 2-3 inches of space between them to allow for spreading.

Bake for 12 minutes. They will be quite fragile at first so don't remove them from the tray until they have completely cooled.