Preheat your oven to 300°F (150°C).

In a large mixing bowl or food processor, combine all-purpose flour, icing sugar, a pinch of salt, grapefruit zest, and fresh thyme leaves. Blend these dry ingredients, then add cubed cold vegan butter and continue blending until a soft dough forms.

Lightly grease a 9-inch fluted tart pan and transfer the dough, pressing it evenly. Bake for 35–40 minutes until edges are golden.

Remove from oven and allow to cool for about 10 minutes. Slice into 16 pieces while warm and let cool completely.

Mix icing sugar with fresh grapefruit juice until smooth. The icing should be pourable but thick enough to coat cookies.

Dip each cookie top into the icing and let excess drip off before cooling on a rack.

Sprinkle fresh thyme or pearl sugar on top of the icing while still wet. Allow cookies to dry completely for 30-60 minutes.