Can chicken be partially deep fried to fully fry later?

Stephie's answer covers the main issues. I would add that you should probably check with any government regulations about food handling. I don't know where you are located, but many states have guidelines about how commercial cooking operations must handle "partially cooked" foods, often requiring documentation of your process, temperature and time monitoring records, labeling of all partially cooked containers (and separation from other raw or cooked food), etc. In the U.S., these are often closely related to the FDA Food Code. (Partial cooking regulations are generally a little more complex than any "2-hour" or "4-hour" rule which is often brought up here.)

Particularly if you plan to try Stephie's 3rd method of partial cooking followed by cooling to refrigerate or freeze, there are generally very specific practices about the amount of time spent during partial cooking and the amount of time spent cooling (sometimes in specific temperature ranges). Usually this method is best for bulk batches prepared in advance, so you have time and attention to monitor the process. That's why most fast-food restaurants that use this method tend to do this as a large-scale industrial process in advance, then ship out the partially cooked frozen or refrigerated food to be simply heated and served.

And if you are going to try to implement Stephie's 2nd method (holding for short times without temperature control), you'll want to have logbooks to keep track of holding time and label every container of partially cooked food. You'll also need to be absolutely certain to keep various batches separate to avoid cross-contamination between partially cooked food, particularly if some of the food may not have reached 140F before holding.

In general, the safest and easiest thing to do is generally to bring food to at least 135F and hold it there. (I should note that the 2013 revisions of the Food Code say 135F minimum for holding, instead of 140F; this change has not yet been implement in most FDA consumer guidelines, but it's now the standard for commercial cooking.) Trying anything else requires a lot more attention to detail to prevent potentially dangerous bacterial growth. That's the reason behind the complex Food Code regulations covering partially cooked foods; there's a much greater likelihood of making people sick if you're not careful.

Partially fried food is a common staple in the fast-food industry and likewise in convenience food at home - you can buy frozen, pre-fried meat or other food.

But you need to keep in mind that all meat falls in the "risky food" category which should not be kept in the "danger zone" 40-140 °F (4-60 °C), for more than 2 hours. If you pre-fry, you will bring the meat right into that zone because heating it above that threshold would mean it's fully cooked.

Taking that into account you have three options:

1. Fully cooking the meat, keeping it warm above 140 °F (60 °C) then just reheating it for the customer.
2. Partially cooking the meat, storing it for no more that two hours and finishing it for your individual customer.
3. Cooling the (fully or partially fried) meat as quickly as possible below 40 °F (4 °C) and reheating or finishing it for your individual order.

As for the feasibility of each option:
1. might cause your meat to dry out and breading go limp, especially if stored too hot or too long and you need to monitor the temperature of your storage device,
2. needs good management of which batch was started at what time and can possibly mean you have to discard a lot of food.
3. has very little advantage as far as saved time is concerned - if at all.

For a very extensive discusdion on food safety and temperatures, see our canonical Q/A on storing food.

Yes you can pre-cook your chicken weather it is seasoned chicken chunks for stir fry or battered or un-battered fried strips or wings. You just cook then in the oven or deep fry them at a much lower temperature for a longer slow cook untill they just get fully cooked them cool off before bagging them up so they won't stick together or steam up in the zip lock bag for freezing untill your ready to double fry them to heat them up along with given them a golden color and a crispy outside but tender on the outside. They only take about 3 minutes at 350 degrees to get them hot and golden crispy brown. Or stir fry them in a wok for the same time with a little oil due to the wok gets very hot quickly flash frying your chicken. Upon the first initial pr-cooking your chicken will look whites and not crispy at all but the double fry will do the trick. This is a quick way to cook for your customers and not getting and slack from food inspector on and raw food cooking or under cooked food. Much cheaper than buying already pre cooked when you can do it yourself for a lot less. I am a food vendor and have done this for years and my customers love how crispy my chicken is and moist and tender on then inside. I have a great trick for burgers as well using a microwave first but not just sticking them in and cooking them. That will not do it. I do not add any juice or flavoring to the Burger either and I cook them from frozen to ready to eat in 3 minutes as well nice and juicy not dry or hard. I have everything pre cooked but not even a trained chief would guess that my food it not freshly cooked to order. I have final mastered what many have tried and failed at. Good luck and always cook good guilty food and always take care of your customer like it was your family. Take Care from MDE