How to use your voice to add items to a shopping list? With iOS Siri, you can say "Add tomatoes to my shopping list" and it will add it to a list titled "Shopping List" in the "Notes" app, easy.

In Android, using S Voice or Google Voice, if you say "Add tomatoes to my shopping list" it will google that, which is unhelpful.

Ideally there should be a way to add items to lists generically in Google Now. Is there such a workflow? 

I am aware Grocery IQ app has Voice entry, but then the workflow is tedious: Hold a button, say OK google, say Open Grocery IQ, then tap a mic, then Say tomatoes.
You can now say "Ok Google" followed by "Add Chicken to my Shopping List" via Google voice recognition app. See a list of Google now voice commands here.