Some great suggestions posted! I too would mostly like to have an improved user interface. For me, that means some of what has been mentioned, and some new:
1- As you suggested in a response above @jordan, I really think the home page should NOT be recipes. Add a higher-level home page that does 3 things: links to the recipes, controls the APC time and temperature directly, and queries the status of the APC at any point for temp and remaining time. Keep the "Settings" gear on the new home page for things like Bluetooth pairing, version number, Fahrenheit vs. Centigrade, etc.
2- Really focus on reducing unnecessary keystrokes, especially for mobile devices. The suggestion above discussing the two taps needed to get to the search keyboard is an example of an unnecessary tap.
3- Broaden the search terms to include more of the recipe ingredients. I don't think "salt" needs to be searched, but the lesser-used ingredients could be very helpful. For example, I might want to use up some kaffir before it turns, but the search reveals no recipes. However if I search for Thai, one of the recipes calls for kaffir leaves.
4- Broaden the search to be more flexible in recipe titles. For example: if I search for "Thai Salad," I'm told there are no recipes. But if I search only for "Thai", 14 recipes come up of which 8 are salads.
5- Recipe "categories" is essential, just like in any cookbook. "Seafood" should give me meaningful sub-categories, or at least a list of all the seafood recipes available in some order (alphabetical by species?). As it is, searching for "Seafood" only shows one recipe for cioppino.
6- As a user interface paradigm, the scroll list for temperatures is a no-no...the list of allowable entries is far too long. Worse, the default entry is the lowest at 41 degrees F. Default should be a more typical temperature to start and then be fine-tuned from there. That said, scroll lists are great for when you have too many items for radio buttons or direct click buttons. But as lists get longer, scrolling loses all its charm. For a range as large at Fahrenheit temps, it would be far faster to just type it in as others have mentioned. Tapping on the temp button should bring up an entry field, open the keyboard, and change it to numbers. And no number should be allowed outside the range of the APC itself, i.e., most significant digit can only be a "0" or "1", decimal digit can only be "0" or "5".
7- Lastly (for now), I strongly recommend the next version of the APC itself and without using the app reinvent the way to set the timer from the very non-intuitive approach now (hold a button for so long, set time, lose temperature setting, reset temperature, swear at device, have martini) to maybe a simple time button (the light is already there...change it to a pressable button) that allows setting time without disrupting temp.
Although it probably doesn't sound like it, I do love my APC; it has created some absolutely superb meals (3-day ribs earlier this week was one), and the companion app has value. The recipes are well-written for easy following, the color photos are appreciated, and the ability to control the APC from the recipe is brilliant. As customers, of course, we will always want more.