Preheat oven to 375 degrees. Line a muffin tin with paper cupcake liners.
Mix the oil and sugar with a mixer on medium speed. Add the lemon juice and water and mix until blended.
In a separate bowl, combine the flour, baking soda, salt, and lemon zest. Whisk together. Add the dry ingredients to the wet ingredients and mix just until smooth.
Spoon the batter into the cupcake liners.
Bake at 375 degrees for about 17-20 minutes until the cupcake tops are lightly golden brown. Cool on wire rack.
Make the frosting: Rinse the six blackberries, then place in a fine mesh sieve over a bowl. Use the back of a spoon to press the juice out of the berries, letting it fall into the bowl.
Cream the vegan buttery spread and blackberry juice, and slowly add the powdered sugar. Alternate adding the powdered sugar and non-dairy milk until you get the consistency you want.
Pipe or spread frosting on cooled cupcakes. Top each frosted cupcake with one blackberry. Store frosted cupcakes in the refrigerator.
Notes
You can use any neutral tasting oil that works for your diet.If you aren't dairy free, feel free to use melted butter and regular milk.Store cupcakes in an airtight container for a day or two on the counter, or for longer in the refrigerator.These should freeze well - just wrap them in waxed paper and store in a freezer bag or container for up to three months.