In a bowl containing egg yolk, add lemon juice and salt. Beat well with an electric mixer.
When it is well mixed, add vegetable oil a little bit at a time, beating after each addition. The mixture will start to thicken.
Add the powdered sugar and beat again. It's even better if you can heat the bowl over warm water at 60℃ (140℉).
Sift the dry ingredients once more, adding them into the bowl and lightly fold in.
Once the dough comes together, wrap in plastic wrap and leave in the refrigerator for more than 30 minutes.
Preheat the oven to 170℃ (338℉). Roll out the dough and cut into shapes with any cookie cutter.
I made them look like shortbread cookies this time. I used a chopstick for designing.
Bake for 13 to 15 minutes at 170℃ (338℉). Baking time make differ a bit depending on the oven.
This time, I used this particular lemon juice product.
How to make plain cookies: Add a little over 1 teaspoon of lemon juice instead of 1 tablespoon. You can make it into cookies or a tart crust for those who don't like it too sour.
How to make lemon tea cookies: Add 1 tablespoon of tea leaves at step 4 and stir. I recommend using Earl Grey tea!
How to make Okara Lemon Cookies (Recipe ID: 555885): These cookies contain okara and are made with vegetable oil. For those who are health-conscious.
How to make Milk and Milk Matcha Cookies (Recipe ID: 556432) These cookies taste of condensed milk and are made with vegetable oil.
How to make Chocolate Cookies (Recipe ID: 556963): These cookies taste very rich and are made with vegetable oil.
Story Behind this Recipe
Since it's become harder to get butter from the store, I wanted to make a cookie made with vegetable oil that didn't taste inferior to that made with butter.
If the egg yolk is not at room temperature, it'll be hard to get it to emulsify. Add vegetable oil little by little and beat well. You can make this into a dough for plain cookies by using only a little over 1 teaspoon of lemon juice. I'm sure it's also good if you put in some finely cut lemon peel. It will taste lighter if you use powdered sugar.