Preheat oven to 350°F/180°C. Line a 9x9-inch square pan with foil. Give the foil a light coating of vegetable spray.
Combine flour, butter, and powdered sugar in a food processor and pulse for several seconds, until combined, but still crumbly. Press into the bottom of the prepared pan. Top with either the Tofu Lemon Curd OR the Simple Lemon Curd.
For the Tofu Lemon Curd (Option #1)
If you're making your lemon bars with the tofu lemon curd: In the same food processor bowl (no need to wash it out), add the tofu, lemon zest, lemon juice, sugar, cornstarch, nutritional yeast, and turmeric. Pulse until completely smooth. Pour the lemon filling over the crust and evenly distribute across the pan.
Bake for 25 to 30 minutes, until the sides are golden brown and the filling is firm (if it's still overly jiggly, you should cook it a few more minutes).
Remove from the oven and allow to cool. After it's cooled, transfer to the fridge and chill for 1 to 2 hours. Once chilled, grab both sides of the aluminum foil and remove it from the pan.
For the Simple Lemon Curd (Option #2)
If you're using the simple lemon curd, in a saucepan combine the lemon juice, sugar, milk, and cornstarch. Stir to combine the cornstarch. Cook over medium heat while stirring constantly to dissolve the sugar and to prevent lumps as the mixture thickens. Bring it to a low boil, then reduce heat to simmer and cook for 2 to 3 minutes, stirring constantly. The mixture should get fairly thick. If you get lumps, simply pulse the curd in a food processor or use an immersion blender.
Once the mixture thickens, remove from heat, add the lemon extract, coconut oil, and turmeric. Stir to combine. Spoon out the lemon curd over the prepared crust.
Bake for 30 minutes, until the sides are golden brown and the filling is slightly firm. It may be a little jiggly.
Remove from the oven and allow to cool. After it's cooled, transfer to the fridge and chill for 2 to 3 hours. Once chilled, grab both sides of the aluminum foil and remove the bars from the pan.
Sprinkle the tops of the bars with powdered sugar. Slice into bars and serve.
Store lemon bars in the fridge. They will keep up to 5 days.
Be sure to tamp the crust down in the pan. This can help prevent the crust from rising to the top while baking.
Option #1 calls for "silken" tofu. You can find that in the produce sections of a lot of U.S. grocery stores and definitely at health food stores. It may or may not be refrigerated and most typically I find it in a small "box" type container rather than a plastic tub. If you can't find silken tofu, then buy a soft or medium regular tofu. The nutritional estimates are provided for the tofu curd.For Simple Curd (option #2), be sure to allow the curd to thicken in the saucepan before proceeding. Also, use the kind of coconut oil that is solid at room temperature.You can sub coconut oil for the vegan butter in the crust.