To make the ladyfingers, preheat your oven to 350° F. In a large bowl, whisk together flour, corn starch, salt and baking powder. Set aside.
In the bowl of a stand mixer, add the aquafaba and cream of tartar. Using the balloon whip attachment, whisk on high until the aquafaba whips into stiff peaks, about 8 minutes (if using a hand mixer, it will take up to 12 minutes). Make sure to scrape down the sides with a spatula, as needed.
Once you achieve stiff peaks, gently add in 90 grams of the sugar. Whip at high speed until the mixture is stiff and glossy (about 2 minutes).
Using a hand mixer, mix the vanilla extract, melted butter, ground turmeric, remaining caster sugar (50 grams) and silken tofu on high until completely smooth (around 2 minutes). This is the “custard” mixture.
Gently fold the whipped aquafaba mixture into the custard mixture by using a circular motion around the bowl and then cutting down the middle to incorporate the aquafaba. Continue this motion until the meringue is completely incorporated and the mixture is pale yellow.
Gently fold in one third of the flour mixture, until completely incorporated. Incorporate the remaining flour, one third at a time. Once mixed, the dough will be fairly sticky and thick (much thicker than a cake batter). Scoop the pastry dough into a piping bag fitted with a 1/2-inch plain tip. You can also just use a plastic Ziploc bag with one of the corners snipped to make a 1/2-inch hole.
Line a baking sheet with parchment paper (I usually end up needing two baking sheets, so plan ahead). If you want uniform ladyfingers, use a ruler to draw lines 4-inches long on the parchment paper (make sure they are about 2 inches apart as the cookies will spread in the oven). Flip the parchment paper over so that the side with the pencil markings are down (you don’t want graphite on your cookies!). Dab little bits of the dough on the underside of your parchment paper to keep it in place.
Pipe 4-inch long “fingers” onto the parchment paper, leaving at least ½-inch between the fingers. I usually end up with about 18 ladyfingers. Dust the fingers generously with powdered sugar and then place them on the center rack of a preheated oven. Bake for about 14 minutes, until the cookies are fairly solid. Set aside and allow them to cool for at least 20 minutes.