To prepare filling, add chopped strawberries, raspberries, sugar in a sauce pan and cook on medium flame for 5 mins. Use a fork to smash in between to get smooth consistency. Add chia seeds, mix everything and turn off the flame.
Chill prepared strawberry mix.
In a large mixing bowl, add flour, sugar, butter and mix till butter is well incorporated in flour.
Add milk and start kneading to get soft dough consistency. Add 1 tbsp more milk if needed.
Dust rolling surface with flour and start rolling dough to get thin sheet like form ( not very thin ).
Using a cookie cutter cut rolled dough into circles ( get as many as possible ) or use a knife to get equal size small rectangles/squares.
Prepare baking tray by lining parchment paper. Place one cut circle dough on baking tray, add 1 tsp ( or more if fits ) of chilled strawberry mix, place another cut circle dough on top and bind together using fork.
Repeat till dough is finished. Bake at 350 F for 20 mins.
Let baked tarts cool before adding icing. For icing, just mix 1/4 cup icing sugar with 1 tbsp of chilled milk.
Serve as it is or with sprinkle of dried raspberries.
Notes
Can use chilled Coconut Oil in place of Vegan Butter.
Use regular Butter and Milk in place of vegan Butter and Milk for Vegetarian option.