Puree or mash 1 cup strawberries in food processor or by hand.
Combine sugar and corn starch in a small saucepan. Gradually stir in water, lemon juice and food colour. Bring to boil over medium heat, stirring constantly; boil 1 minute. Let mixture cool slightly.
Gently stir remaining 3 cups sliced strawberries into cooled filling. Spoon into tart crusts. Refrigerate at least 1 hour, until set and chilled.
Top with whipped cream and blueberries. Tarts are best served the same day prepared.