For Sours that call for a foamy head, we follow a shaking method that, for us, is foolproof when using a foaming agent. The method is:
1 shake all ingredients, except the foaming agent, with ice
2 fine strain into a mixing glass
3 dump ice from the shaker
4 pour cocktail mix back into the shaker
5 add foaming agent
6 dry shake
7 remove cap and lid from the shaker and pour into serving glass - the foam will dispense last, allowing one to make the head as fluffy as one wants it.
1 shake all ingredients, except the foaming agent, with ice
2 fine strain into a mixing glass
3 dump ice from the shaker
4 pour cocktail mix back into the shaker
5 add foaming agent
6 dry shake
7 remove cap and lid from the shaker and pour into serving glass - the foam will dispense last, allowing one to make the head as fluffy as one wants it.