How to Make It
1. Heat oven to 350˚F. Lightly butter six four-ounce ramekins (mason jars work perfectly) and dust each with sugar, shaking out any excess.
2. In a small bowl, mix 1/2 cup sugar (reserve the other 1/4 cup sugar to whip whites with) with flour and lemon zest. In a large bowl, lightly beat egg yolks, and stir in the buttermilk and lemon juice.
3. Whip your egg whites until softly peaked while slowly adding rest of sugar to ensure a silky texture. Whisk sugar mixture into buttermilk mixture, then fold in beaten egg whites in thirds. Spoon about 3 oz batter into prepared containers. Place in baking pan, and add hot water to pan to come halfway up sides of ramekins or tins. Cover the pan completely with foil.
4. Bake about 15 to 20 minutes until batter begins to puff. Remove foil, and bake another 5 minutes or so, until tops begin to brown and are springy to the touch–a little cracking is fine.
5. Remove from the oven, and allow to cool for 15 minutes before inverting onto serving plates. You can serve them warm. The top will have a beautiful clear curd-like texture and the bottom will be light, spongy and airy. If you make the pudding in advance, allow it to cool to room temperature, and store it in the fridge. Unmold to serve, or reheat in warm water bath, and serve warm.