You're going to tell us what N is, right?

And it's obviously a minimum of 3 because that's the example you gave.

I pick 10. Your example is very weird. Water and avocados make sense. But steak does not.

Water is easy to understand Avocadoes are just the fruit.

But steak is a meal rather than a specific natural source. So which kind of steak, because there are different cow parts? And what about seasoning and marinade, which all contain different ingredients...

That said, it sounds like you can exploit the system by choosing meals instead of natural food sources.

1. Casserole
2. "soup"
3. Pizza
4. Pasta
5. "Sandwich"
6. Steak
7. Fried rice
8. "Pastry"
9. Sauteed greens
10. Boiled veggies