Hi Micheal
This is a tough one! I have IBS and I can give you some suggestions but the triggers are different for some IBS patients.
I use sweet potato instead of potato even for making chips.
100% Rye bread of pumpernickle instead of regular bread.
Goats milk dairy products since they are easier to digest.
Basmati rice
Rice Noodles intead of pasta
Lentils are easier on the digestion than beans and can be used for many dishes. Curries, binder for fishcakes or cooked as your starch component to a meal.
I avoid raw onion, raw peppers, green peppers I don't eat at all!, remove the skins from cucumber and the seeds, raw cabbage etc. These cause terrible discomfort.
You can also use bulgar wheat, whole sorghum or barley as a starch.
Beetroot is very gentle on the stomach so I use those a lot.
You can make roots mash as a side dish using sweet potato, turnip, butternuts etc, instead of potatoes. All of these make great fries.
Butternut is good baked with garlic, black pepper and olive oil as a savoury dish.
You can make fish stews with veggies and serve with basmati or rye bread.
You could make fish or seafood parcels with fresh veggies of choice.
Blending cooked lentils and fish with spices and one egg make a good fishcake. You could use rice flour and crushed corn flakes for a crumbed coating.
White sweet potatoes are not very sweet so they make a good topping for fish pie.
I could give many ideas but it's difficult if you don't know exactly what a persons dietary needs are.
I use medication for my IBS so I don't restrict my diet as much and I still eat the foods I know I shouldn't sometimes and just deal with the discomfort. I don't have the willpower to cut out all of the things I love from my diet.
I hope some of this helps