There is a saying is that the definition of insanity is to continue doing the same thing over and over and expecting different results.
Yes, you need to cut the menu down. Right away. Congratulations on recognizing the obvious. I mean that sincerely. I am always amazed when restaurants don't see a problem
that seems obvious to me.
The trade show arrives. Again.
You can do several things in response.
1. The same thing you've been doing and hope it gets better.
2. Enlarge the kitchen with better equipment. Very expensive requiring restaurant shut down. That's not realistic.
3. Make the dining room smaller to serve fewer people. Obviously not a smart or realistic response.
4. Reduce the already too large menu.
I can't imagine you are doing this without a point of sale (POS) system. That system records every sale of every item and can generate sales reports for any length of time
you choose. A day, week, month or year. By the hour even.
If the owner does not know how to do this, the POS representative should be asked to come by and show her how. ASAP.
Print a report of all items sold in the previous six weeks. Or six months.
Review sales report for regular business times and then for sales during the trade shows. Are high selling menu items the same?
Review the report to discover which items actually sell in large amounts.
Review how many extra ingredients you invest in for those dishes that don't sell as well. How much money is going into having those ingredients on hand for the limited sales. That money includes the ingredients themselves, storage area, labor time, maintenance of quality and time and energy spent worrying about all of it.
Keep the top selling items. Get rid of everything else. Then you can develop any additional, suitable menu items based on the ingredients used for the top selling menu items.
The POS provides actual sales reports, not sales based on human perception. "We sell a ton of those". No, you don't. (more on that later.)
Step two Communication. Review your customer base before and during a trade show rush. If the owner is familiar with the regulars by name this will be easier.
If not, a survey can be created and given to them during regular business. To wit "As a valued customer, we would like to know if you ever patronize this restaurant during trade show insanity?"
"If Yes, what would you like to see? If not, what are you avoiding?" You create the survey asking whatever you want and the regulars will be thrilled to know they are being included in the decision making process and that their opinion matters.
I suspect the regulars know to avoid the place during those trade show rushes. So retaining menu items for the sake of the regulars during a time when they are not really there doesn't make sense. And if the regulars do patronize the place they will understand why there is a limited menu, knowing that they can come back after the rush knowing they will get their favorite items.
All patrons, trade show or not, wish to have a pleasant dining experience. All employees wish to have a busy but orderly service. Jamming a size twelve menu into a size eight restaurant does nothing for either.
More on sales perception. Neither you nor the owner nor anyone else really knows what actually sells well. To illustrate, consider two menu items.
Item one is easy to prepare and serve. Order comes in and with very little effort is prepared and served. The dish is well plated but not visually notable.
Item two is a bit more challenging. Order comes in and a fair amount of attention and detail is required to prepare and serve. Dish is visually notable when plated.
If asked, the cook will say that item two sells a lot. Item one sells well but not like item two. This perception arises out of the greater attention to detail and focus required to get the dish out in a timely manner. The first dish flies under the radar, so to speak.
In the FOH, the staff will remark that item two sells well. This perception arises because of the visual impact or the challenges in serving it.
Neither is accurate. A POS sales report will prove beyond doubt what actually sells.
I have experienced this first hand and removed several "popular" dishes from the menu when the POS sales report showed that it wasn't just not popular, it was the sixteenth on the list of sales items. Challenging to prepare and visually notable but not popular.
The POS is a powerful tool at your disposal to help make many decisions about the overall restaurant. Successful management requires understanding what is actually happening by accurate measurement, exactly like thermometers telling you the actual temperature, not just that it is warm or cold.
Technology today offers a restaurant owner the ability to have a clear picture of the financials involved. Record keeping for inventory, recipes, sales and maintenance can now be kept track of by use of computer software when it is used correctly and to full advantage, offering an instant and accurate portrait of restaurant expense and profits. I used Quickbooks and MaitreD POS but there are others.
Your initial post tells me the owner is not doing this but instead relying on perception. That is a big mistake.
I'll go so far as to offer that you can print this out and show it to her.