Hong Kong egg tarts

Time: 4 hrs
Yield: 24-28 tarts
Adapted from Taste Asian Food
Ingredients (Measurement, Percentage):
Oil dough:
AP flour: 200g / 100%
Butter: 325g / 163%
Water Dough:
AP flour: 150g / 100%
Sourdough discard: 200g / 133%
Egg: 50g (1 egg): 33%
Salt: 3g / 2%
Custard (recipe from
Eggs, room temp: 250g (5 large)
Milk, room temp: 80g
Water: 165g
Caster sugar: 80g
Vanilla extract: 4g
Make the oil dough. Add butter and flour to food processor. Pulse until a paste forms. Form into a rectangular block, wrap in saran, refrigerate for 20 min.
Make the water dough. Combine all ingredients in food processor. Pulse until dough forms. Wrap, chill in refrigerator for at least 20 min.
While dough is chilling, make custard. Combine boiling water and caster sugar together, stir until caster sugar is dissolved. Set aside to cool to room temp.
Mix eggs in one bowl. Mix milk and vanilla extract in another bowl. Once the sugar water is room temp, add milk and vanilla extract to sugar water, mix until combined. While whisking the eggs, stream in milk mixture.
Strain twice through a fine mesh sieve, cover and set aside until ready to assemble tarts.
Time to laminate the oil and water dough! I recommend rolling with plastic wrap because this will make the process much easier.
Take both doughs out of fridge. Cut out two large pieces of saran wrap. Flour one piece of saran wrap, place water dough on floured saran. Flour top of water dough and place other piece of saran wrap on top. Roll out until the dough is in a rough rectangle. Remove top saran wrap.
Place oil dough in middle of water dough. Take edges of water dough and stretch to cover the oil dough. Place saran wrap on top of rectangle. Roll out until 3x in length.
Using the saran wrap, fold one side over the center. Fold the other side over the side you just folded (it will look like a letter). At this point, if the dough is getting warm, chill in freezer for 5-10 min.
Repeat this 2 more times. Chill in freezer for 10-15 min.
Preheat oven to 450F.
Roll out until 1/8-in thickness. Cut out 4-in circles. Place in tart tins. If dough is warm, put in freezer to for 5-10 min. Once tarts are cold again, prick the bottoms - careful not to prick through the tin.
Pour custard into tarts, until 80% full.
Place on a shallow baking pan and transfer to oven. Immediately turn temperature down to 400F. Bake for 10 min at 400F. Reduce temperature to 350F. Bake for 15 more min, rotating baking pan if tarts are unevenly browning.
Remove from oven, eat warm or wait to cool!