I carry the following in quart size Zip Lock freezer bags
Hard boiled eggs
Pinto beans
Cheddar cheese
Whole wheat crackers
Frozen mixed vegetables
Several slices of bread
Dried fruit - apricots, figs
Nuts - almonds, walnuts

Sliced beef/pork/chicken - I cut into pieces in advance and freeze at home

Protein bars
Mini bags popcorn

Plain Greek yogurt in a small plastic bin

8 inch thin/light plate in the suitcase
Titanium fork/spoon for camping

I use a Strong Bags Canadian Ice Cooler. It's better insulated and stays cold longer than the other coolers on the market. There's usually a refrigerator in the hotels we stay to maintain the food overnight. If not, the Strong Bags cooler with ice in zip lock bags will maintain it.

There's always a microwave available in the hotel to heat the beef/pork/chicken and frozen vegetables.