Sift the flour, baking powder, bicarbonate of soda and salt together into a large bowl. Stir in the sugar, lemon rind and poppy seeds.
Mix the oil, rice milk and lemon juice together in a jug. Add to the dry ingredients and stir to mix. Spoon evenly into a 12-hole muffin tin lined with paper cases and bake in a preheated oven, 160°C (325°F), Gas Mark 3, for 15 minutes until just firm to the touch. Leave to cool on a wire rack.
Beat the spread, icing sugar, lemon rind and food colouring for the frosting together in an electric mixer or in a bowl until soft and smooth. Spoon or pipe the frosting on to the cooled cakes and sprinkle with the remaining poppy seeds.