Looking at this photo, I can almost hear Robert Irvine saying, "all's I want is..."
The use of this contraction has never jumped out at me as much as it has while watching Restaurant Impossible. Which got me to wondering what exactly is being elided because the contraction is not found in any dialect with which I am familiar. Initially, I thought Irvine was combining "all" with "is" (even though they are not adjacent) and then repeating "is".
Good thing I looked it up. The New York Times article by Ben Zimmer titled "All's I Know" reminded me that I should have checked the Dictionary of American Regional English for unusual usages. There I would have learned that what is being combined is "all" and "as" with "as" being used as a relative pronoun similar to "that".
All that I wanted was a syntactic clarification. All that I know is I got it. Thank you Ben Zimmer and DARE.