Combine rum, vodka, lemon juice, strawberry syrup, and milk in a bowl. Allow this mixture to sit for about 30 minutes so that the milk can curdle. Strain the liquid slowly through a coffee filter until the base is completely clear. Pour the clarified base into a chilled tulip glass over a large ice cube. Dispense the strawberry foam over the ice cube so that it forms a separate, distinct top layer on the drink.