Brioche au Citron Questions

My dough is still sticky after 10 minutes of kneading - did I do something wrong?

A slightly tacky dough is normal here, because 40 g of soft butter and a whole egg go into only 250 g of flour. Keep kneading rather than adding flour; the dough should pull away from the bowl and feel smooth and elastic. Add extra flour by the teaspoon only if it is still soupy after the full 10 minutes, since too much flour will cost you the ultra-soft crumb.

Can I use bottled lemon juice, or do I need fresh lemons?

You need at least one fresh lemon, because the recipe calls for the zest of a whole lemon and that is where most of the aroma sits. The juice itself can be bottled in a pinch, but the 1-2 tbsp in the cream and the 1½ - 2 tbsp in the glaze taste noticeably brighter when fresh. Since you already have a lemon for the zest, juicing it usually covers both.

How do I store the filled brioche and how long do they keep?

Once filled, the buns contain an egg-yolk-and-milk cream, so keep them in the fridge in a covered container rather than at room temperature. Take them out 20-30 minutes before serving so the brioche softens again, as the crumb firms up when chilled. Unfilled baked buns keep better in an airtight container at room temperature.

Can I prepare parts of this in advance?

Yes - the lemon cream is the best make-ahead component, since it has to be covered directly with plastic wrap and cooled completely anyway. Make it a day ahead, refrigerate it, then whisk it smooth before filling. You can also bake the buns in advance and fill and glaze them shortly before serving, which keeps the glaze crisp and the brioche from going soggy.

Why did my lemon cream turn out lumpy or thin?

Lumps usually come from pouring the hot milk into the yolk, sugar and cornstarch mixture too fast - add it gradually while whisking, then cook until thick. A thin cream means it did not cook long enough for the 15 g of cornstarch to set; keep stirring over heat until it visibly thickens. Also stir in the lemon juice, zest and butter at the end, and cover the surface directly with plastic wrap so no skin forms.