I've been experimenting with this approach and have one more technique to add.
If you have certain dishes that you like to make, try making a sub-project for one, and listing the ingredients underneath it. For example, I have:
- Pizza
- Whole wheat pizza dough
- Canned tomatoes
- Mozzarella
- Basil
Add contexts for each item, so you know where to buy what:
- Pizza
- Whole wheat pizza dough — Trader Joe's
- Canned tomatoes — Whole Foods
- Mozzarella — Trader Joe's
- Basil — Trader Joe's
Then, before you go shopping, you can just uncheck all the items beneath "Pizza" and know that you didn't forget anything, because you've already documented it. (You're so smart.)
Switch to your context view (whether on your iPhone or for a printed copy) and you'll see all those ingredients sorted by store, e.g.:
Store > Trader Joe's
- Whole wheat pizza dough
- Mozzarella
- Basil
Store > Whole Foods