For me, I've found it doesn't really matter what I eat for lunch...but it does matter what I eat for breakfast.

I usually have

Hummus and raw veggies

Or

Egg and cheese sandwich on light whole wheat bread

Or

Whole grain salad where the base is something like quinoa or wheat berries and it has some sort of seasoned olive Oil dressing mixed with veggies, beans, feta, etc

And

I also add some sides like a small portion of olives, piece of fruit, small portion of nuts, plain yogurt with a bit of honey and some walnuts thrown in

That's all I got. I'd stay away from pasta and pizza. Also, drink lots of water.

Coffee or 5 hour energy

The answer is eggs. They give me energy when nothing else will. Easy ways to bring them to work would be hard boiled, as egg salad, as a frittata, made with any kind of ingredients, good hot or cold.

I found exactly the same thing as OP, and really salad with protein is the only thing that keeps me from crashing. However, any type of greens and veggies work, so I try to vary them. Also, I've read studies that say that vinegar helps regulate blood sugar, so I think the vinegar dressing is part it, in addition to avoiding carbs.

I have scrambled eggs or oatmeal every morning and chicken salad with apples every lunch. Boring but works for me. I do feel the crash in the afternoon if I go heavy on carbs.