Preheat the oven to 400 degrees F.
Combine the milk, zest
and lemon juice
in a tall glass. Refrigerate and allow to curdle
for 10 to 15 minutes, until thick. Sift
together the flour, a generous pinch of salt, and baking soda into a medium bowl. Using your fingers gently mix in the butter until an even, but grainy texture is reached, being careful not to melt
the butter as you work. Add the soured milk and scallions and stir until the dough
comes together. (Dough will be sticky.) Gather the dough into a ball, and refrigerate 15 to 20 minutes, until chilled.
Transfer the dough to a floured surface and knead 3 to 4 times until the dough is smooth. For fluffy biscuits do not over knead
the dough! Roll out the dough to about 3/4-inch thickness. Cut with a 3-inch pastry
ring or the top of a glass. Arrange the biscuits
on a parchment-lined sheet pan
. Allow the biscuits to slightly touch and gently adhere when baked. Bake until biscuits are golden, about 15 minutes. Remove from the oven and transfer to a bread basket or bowl and serve.