This trick requires two bottles, and a telescope. Go to Grandma's and fill one bottle with Elixir. Set the bottle of Elixir to Y. Press Start + Y, then put an empty bottle in Y, where Elixir was located. You will now have two bottles all together; one bottle full of Elixir, and one bottle half filled with Elixir. Set the full Elixir back to Y. Press Y + Start, then select the telescope on Y. You will drink the Elixir, but keep a whole bottle. This can be repeated as many times as needed. Additionally, set one bottle of Soup to Y. Press Y + Start and put an empty bottle in the slot that the Soup occupied. Press Y + Start and you will have one full bottle of Soup and a half a bottle.