In a mixing bowl, beat the margarine and sugar together until creamy. In a small bowl, mix the egg replacer and water together. Add the egg replacer mixture, vanilla, and salt to the margarine and sugar mixture and mix until combined well. Add the flour gradually while mixing until fully incorporated.
If desired, add food coloring to the dough for tinted cookies (we like green for Christmas trees!) Put the dough into cookie press and press onto ungreased baking sheets. Add decorations such as tinted sanding sugar before baking.
Bake for 5-6 minutes until set but not brown. Remove cookies from baking sheets immediately and transfer to paper towels or a cooling rack.
Notes
Alternative to the egg replacer: Omit the egg replacer and water and instead add 3 tablespoons of aquafaba (brine from a can of white beans).If the dough is crumbly after mixing, add 1 tablespoon of water and mix. The dough should come together into a ball when it is the right consistency.