To make the dough, combine the warm water, yeast, salt and 2 Tablespoons of the sugar in a large bowl.
Allow the mixture to "proof" (bubble) for 5 minutes before continuing with the recipe. At this time, I like to prepare the lemon curd so it is well chilled by the time I need it.
To make the lemon curd, combine the lemon juice and sugar in a saucepan, whisk well, then add in the eggs. Heat over medium-low heat and start to whisk in the butter.
Allow the mixture to bubble for about 2-3 minutes until starting to thicken before removing from heat. Allow to cool (you can transfer into a mason jar after it has cooled a bit to continue chilling in the fridge).
Returning to the dough, add the remaining sugar, buttermilk, egg, and vegetable oil and stir well.
Add in the flour, 1 cup at a time, until well incorporated.
Knead the dough for 5 minutes, then cover the bowl with a clean kitchen towel and allow to rise, about an hour.
Punch down the dough and then roll out on a floured surface into a large rectangle about 1/2" thick. (Use flour to prevent the dough from sticking to the rolling pin as well.)
Spread the lemon curd over the rolled dough and then roll one long side of the rectangle towards the other, forming a tight log.
Cut the log into 2" sections to form the sweet rolls.
Place the buns in the prepared casserole dish and cover with tinfoil, allowing to rise one last time, approximately 1-2 hours.
Heat the oven to 350F and bake the rolls for 17 minutes.