On Saturday or Sunday afternoon, assemble a base salad out of the hardiest salad vegetables: lettuces, carrots, cabbage, radishes, etc. Then you can pull out your base each night and dress it up for that evening’s meal with the more perishable additions: cucumbers, tomatoes, mushrooms, avocado, roasted vegetables, cooked grains or proteins (to make a salad meal), etc. You’ll neeed to build another salad base on Wednesday or Thursday to get through the whole week.
You can also prepare a base meat at this time, such as a simple roasted chicken or poached chicken breasts.