Make the strawberry consommé: Combine the strawberries, sugar and water in a medium saucepan; simmer until the strawberries break down, about 30 minutes. Strain through a fine-mesh sieve (discard the solids) and refrigerate until cooled, about 1 hour.
Make the drink: Combine the lemon juice, egg white, rosewater and 2 1/2 ounces of the strawberry consommé in a cocktail shaker with ice. Shake well.
Strain the drink into a coupe glass. Garnish with a flower.