Im working in a restaurant that has pan-seared greenbeans and sauted chopped zucchini with onions&peppers. It seems were constantly waiting for the damned veggies or GB to complete our plates so the rest of the meal gets effing' cold! After a few batches the pan gets all charcoaly and the veggies get all grainy and ugly. (We use nonstick spray to do the greenbeans and in a separate saute pan we use a soysauce type mix for the zucchini stuff.)
I have seen various establishments par-cook their vegetables then finish them in whatever sauce is being used or quickly reheat them in a pan or on a flat top in oil or butter.
Like part of your morning prep would be to cook off however many zucchinis (broil it? oven fry? up to you, you're making them in bulk so sauteing may not be the most efficient route) you're going to need for the evening, cool them on a half pan in a single layer, then store them in your line until the order comes through. Chuck them in the morning if they don't hold up well overnight, I'm not super sure how well zucchini holds up. Green beans should hold just fine for a day or two.
All you need to do then is get a serving out and saute until heated through. Shouldn't take too long, and it shouldn't leave an unwieldy mess in the pan as long as it's oiled appropriately.
I've never worked in a commercial kitchen, so it's quite possible that this might not be considered acceptable from a safety point of view.
Keep the pan on a flame lower than what you'll need for cooking. (so it's not so hot that things will scorch as soon as you add the food, but warm enough to keep from needing so long to pre-heat the pan.
Another option would be to keep stash it in the oven, but then you'll be working with a hot handle.
It's also possible that some of your problems are a result of the non-stick spray; I don't know what the effect of them accumulating in the pan are. I do know that if you're putting a thin layer of oil in a pan that's too hot, it'll polymerize, creating some nasty orange gunk that's a pain to clean. (it's basically the same stuff that we look for when seasning a cast iron pan)
Have you considered using a griddle pan instead of a frying pan? That way there will be no need for oil, you'll get a nice stripped effect and no specks all over your food. Otherwise, whats wrong with cleaning the pan between each use? There's only 2 pans in my kitchen that don't get washed after each use. That's my griddle and my fried egg pan.
Or in-fact we don't wash our fish pans, as we try to preserve the non-stick as much we can. Instead of washing them we wipe them out with blue roll (Kitchen paper). You could probably do this with your vegetable pans. That way they will still stay hot but not full of burnt badness.
Another possible technique, but again, one that I don't know if it'll be acceptable in a commercial kitchen:
- After cooking, return the pan to the heat, but add some water to the pan. When it comes time to use it, dump out the water, wipe it dry, and then cook your vegetables.
This also has the advantage of helping to slightly clean the pan in between usages. If you want it even more clean, deglaze once, dump that, then add clean water before returning it back to the heat.
You might have to monitor it to make sure that it doesn't boil dry if you go too long between orders, but as the pan's got less residue on it, it should give you less problems if that happens.
Why don't you "pan sear" the green beans on a flat top before service starts then rewarm in the sauce? you also do the saute veg before hand and throw em into the sauce to rewarm?
Switch pans every few batches? use oil instead of the spray? If the oil starts to smoke reduce the flame.
if its the sauteing that takes to long switch to a larger pan?
If you using a stainless steel pan switch to aluminum pan?
If it takes that long to make the veg part you should be firing it earlier.