I discovered a 4-pc grilled nuggets kids' meal from Chick-fil-a with buffalo sauce for dipping and fruit instead of fries is a great lunch - just the right portion size, 145 calories if you get a calorie-free beverage. For a drive-through meal, you can hardly do better! I also like the Vietnamese chicken salad spring rolls from Pei Wei. They're super light and full of lean chicken and veggies.
At sit-down restaurants, I typically order a protein and a steamed vegetable. For example, at Red Lobster, I get crab legs or a lobster tail and broccoli. At a steakhouse I'll get a 7-oz filet mignon and asparagus (and take half of the steak home). At a Japanese restaurant I like to get sashimi, or share a kids' bento box with my 3-year-old. If we're eating at a deli or something, I'll order a sandwich but just eat half. My husband and I shared a sandwich, I ate the fruit that came with it, and he ordered a cup of soup on the side.
You can still enjoy eating out after surgery, you just have to be creative about your portions and sharing!