Good summary. The key point you've highlighted is the need for something at lunch that is not the same as dinner. Everything you've suggested should be readily available at similar total cost if they chose to go that route. The only argument I can hear coming would be storage. I have to wonder if that contributes to the current choices, since having fewer of each item to accommodate more variety could lead to running out of some, with the end result being even fewer choices.So if I had to create something with the current system I would do the following -
Breakfast - Same as now without the breakfast sandwich and instead offer - warm cinnamon rolls or mini waffles and egg bites similar to the ones served at starbukcs (they come pre-made and frozen.)
Lunch - Offer a choice of entree salad or sandwich. The salads and Sandwich plates would be pre-made and would be served with the following choices - Tuna Salad, Turkey, Roast Beef, Veggies and Hummus. Everything would be pre-made so you just add the chosen protein to the chosen salad / sandwich plate. Add a pack of chips and choice of dessert.
Dinner - entree plates would be pre-made with side salad, garnish, and premium cold side dish. Hot Entrees would be - salmon, grilled chicken, beef, and a veg. Entree. The entrees would be heated up and added to the pre-made plates. You could offer choices of side salad and premium cold sides, as they could be pre-made before serving time... or you could just have 1 basic plate. Again add a choice of dessert.
Desserts should include at least 1 gluten free option.
This allows some options for customers to mix and match and customize based on diets. If the above would be too complicated... maybe only offer 1 or 2 choices with the entree plate for dinner and continue to offer the entree salads but not the sandwiches for dinner?