Pre-Paleo I would eat crackers or whole wheat toast with diet ginger ale after vomiting from, say, food poisoning, but I'm not about to go back to my old ways and make myself even sicker.
What does the Paleo community recommend for recovering from stomach illness?
Firstly, make sure you hydrate yourself since vomiting upsets your electrolyte balance. Coconut water is very good. Herbal teas such as chamomile and peppermint (brew a teabag of each) are very soothing on the GI tract and decrease irritation, spasms and inflammation. Lemon & ginger, with perhaps some honey (if you eat it) is also good. Ginger particularly is also anti bacterial and anti-emetic (stops vomiting & nausea).
Bone broth is probably the best way to shuttle in nutrients if you can't keep anything down, and the gelatin is very soothing on the GI tract.
Once you actually feel hungry, well-cooked lean meat (e.g. turkey breast), root vegetables (carrots, parsnips, swede, squash, pumpkin) and some fruit (cooked apples/applesauce, bananas -if you eat them) are best. You can boil some turkey/chicken breast with some root vegetables in some bone broth, and puree for a creamy soup. Similarly, you can cook & puree root vegetables and even cauliflower to make a mash.
Then you can go on to steamed lean-ish meat, perhaps some scrambled eggs.
Lots of water rich with electrolytes since vomiters tend to be dehydrated - coconut water would be good.
Bananas and applesauce are still paleo, and a little white rice never killed anyone.
I strongly recommend fasting until you're hungry (if you have no appetite, there are good reasons your body doesn't want food), and sipping water until then. Once you want food, if you trust your body to be free of addictions, eat what you crave. Your body knows what it needs and will tell you.
I take very dilute bone broth; if I'm feeling strong enough I will take it with a touch of puréed pumpkin or squash. I recently tried Campbells Chicken Noodle -- my pre-paleo go-to -- and found I couldn't stomach it. Now I always keep a frozen bone broth stash on hand.
you can eat and drink anything you want. Part of the reason crackers and soda helped you is placebo and it takes you back to when you were a kid and your mom comforted you with those things.
Say you just vomited and you have that weak/thirsty feeling. You drink a glass of water but are still weak. You open your fridge and the sight of eggs makes you nauseous - don't eat eggs, your body is telling you something. However, the _ looks good or less bad. Eat that.
I know, it's practically rocket science, but if a paleo person 12,000 years ago could eat after vomiting without the aid of refrigeration and the internet, you too can do it too.
Food poisoning is the absolute worst. I feel for you!
A broth with fat & salt works the best. You can use bone broth or if you don't have any, a simple soup made with chicken bouillon. Don't try to eat any solids in the form of veggies, nuts or fruits yet. I've also found that just drinking plain water will not re-hydrate your body--it will just come out the back end the same way it came in ;)
A quick soup recipe that has some protein in it is egg drop soup. Boil 4 cups of water, add in 3-4 bouillon cubes and 1-2 Tbsp of butter. Crack open and scramble 1-2 eggs in a cup, and with a fork lightly drizzle the eggs into the roiling water. Take off heat immediately, wait 5 minutes before serving.