How about various salads?
One bag of salad greens, mixed leaves, rocket salad or bistro salad, a small pot of baby tomatoes and a cucumber as base for all three days - cucumber can be simply sliced one day, lightly picked another, chopped into Greek yogurt with mint to make a simple tzatziki the third day.
Add a protein each day - a small goats cheese, feta, smoked salmon or gravlax, salami, mortadella, ham, prosciutto, chicken, devilled eggs.
Vary the salads with a selection from the following: pomegranate, blueberries, toasted walnuts, olives, chopped figs, radishes, spring onions, crispy onions, croutons, crunchy salad topper.
You can add sides of garlic bread, potato salad, pasta in a yoghurt and basil dressing if you want to add carbs.
You can use one (bottled) cheap French dressing but vary it by adding honey one day, soy sauce and a little ginger another, lemon juice and zest another.