The biggest way to add flavor with restrictions is herbs and spices. You can make the same boring skinless chicken breast into a hundred different treats that way...but you have to know what he likes. Basic different familiar flavor combos include pesto, curry, taco, Old Bay, barbecue.., And start inventing your own. Use a tablespoon of olive oil, or something equally tasty, or an eggwhite, or anything sticky, if you need to make a paste. Thin with wine or vinegar. Cut the protein in different ways on different days for varietly, and grill some, stir fry some, etc. Mix with vegetables with a variety of flavors and textures (and colors). Depending on what's allowed, vary the protein. There are fairly lean cuts of lamb, veal, etc., which might be welcome. All the best for your friend's recovery.

You should gather more information on the likes and dis-likes. Especially the 'like' list. This link, HERE

Low salt and fat is common. But most medical doctors have near zero dietary training.

My FIL was told low salt and fat. Turkey instead of beef. MIL stocked up on turkey legs. He ate them like a savage but no veg at all.

Turkey, turkey bacon, potatoes and tons of sugars. Not a good diet.

Some things like maltodextrin in processed foods can be triggers for some.

A friend of mine that does not cook at all is on the Trader Joe's elimination diet. The frozen veg and grain products without additives.

And yes, spices will add flavor but it needs to be included or on something on the 'like' list.

My visiting gift for years has been cooking for my in-laws and my parents. Every meal made many freezer portions for them. Lots of veg in lasagna, veg and mushrooms in meatballs, soups with grains, beans, greens, and braised skinless chicken thighs....

Sleevendog . . his daughter supplied some info . . . no fish or shrimp, no broccoli or lima beans. I used to go to Fl when my mom was ill to stock up her freezer with things that she liked. Found out later that my kid sister would take them and throw parties with the food I made for my mom then tell her I didn't do anything for her. Mom knew better but the brat still told the lies. For my friend I am only taking 3 days worth of meals. Several other women in my cooking group signed up for different weeks. His daughter can cook a bit for him but she is a VA social worker (and early 20's too . . likes salads and fish) so is very overworked, so we are trying to give her some relief.

My Dad has to be on a low salt diet. Some of the best things for me to make for him are soups because canned soup is a sodium nightmare. I also make baked beans, another high sodium food he likes, the canned version that is. All can be made low fat. Some kind of stuffing or bread casserole would be good too, that's something else my dad likes store bought which is ridiculously high in sodium.

Pasta dishes may also be OK, they can be low in fat, depending on what you add to sauce them. Marinara could be fine, especially if you add extra vegetables but carbonara, probably not so much, LOL. Meatloaf or meatballs made with ground turkey or lean grassfed beef could also be an option, but watch the turkey. Some ground turkey is full of fat and skin and has as much fat as the beef might!

If he likes salads, things like taco salad might work if you skip the salty tortilla chips. Chili might also be good, although I think of that as a "winter" meal, it can be all vegetable and bean with no meat at all and lots of flavor without salt.

Good luck, it's a very nice thing to do.

Annie

Often, on a diet, you miss crispy. You can get panko to stick to chicken with beaten egg white and bake.

If you google weightwatchers recipes online, you'll find lots of good ideas for low fat and low salt is easy.

Oh yeah, meatloaf is also something I make for my dad because a lot of recipes call for seasoned crackers or bread crumbs and onion soup mix. All tasty but LOADED with salt. You can use grated carrots or some other veggie depending on the eater's taste, to add additional moisture to lower fat meats. Even some low fat cheese, in a small amount. Muenster is a lower fat, lower salt option easily available. A seasoned tomato sauce takes the place of gravy. My dad likes this but I tend to make it for him in cooler months as it has to bake for a long time. You could make individual serving sized portions for him to freeze.

Edited to add that my dad likes the baked chicken breasts rolled in buttermilk or thinned yogurt and then topped with seasoned bread crumbs or panko, but season your own, all these pre-seasoned bready things are full of salt. If this guy gets serious, his taste buds will get accustomed to lower salt foods and he won't miss it as much. That's what we found, we cannot abide by most prepared and restaurant foods anymore, due to the salt and saturated fat. We also eat lower salt and lower fat for regular ol' health reasons . . .

This is similar to my recipe, except I use less parmesean cheese because it is both fatty and salty. So I use 1/4 cup. I also use chicken breasts, which I cut up into tender sizes for more meat to coating ratio. I rarely fuss with buttermilk, just use thinned plain yogurt which we have on hand all the time. I am dead lazy, so I often use UNSALTED poultry or Italian or other seasoning blends on chicken rather than specific spices that are listed in a recipe if there are too many . . . . A grind of lemon pepper is also often appreciated in a low salt situation. With this recipe below, make sure your panko or bread crumbs are no salt or low salt. There can be hidden salts in seasoning blends and as I mentioned before, almost any type of bready product purchased over the counter . . . if you live in a big enough market you can usually find the lower salt versions, which are by no means LOW salt, just a bit lower. No such luck where I live. I save my stale bread to make my own bread crumbs. Even regular bread has a lot of salt in it, so don't salt any type of seasoning mix or bread crumbs you end up using.

https://chefabbiegellman.com/buttermilk-baked-chicken/