Obviously it will depend on how many you are cooking for, and how much money you have, but apart from that the choices are almost endless!
The most important thing is to avoid packaged/pre-processed foods, [ ... as everybody else is saying ... :lol ... just cross-posted with another person saying this
... ] , as gluten and casein tend to be everywhere in those, ( including soy sauce as others have said; a good gluten-free soy sauce is "tamari" ), eg. hydrolysed vegetable protein is gluten for instance and crops up a lot; gluten is also routinely used as the "base" for many spice and flavourings, eg. in crisps/corn chips etc ( and often not mentioned in the ingredients ).
If you want to serve a fairly traditional protein, carbohydrate and veg/salad meal use rice, or corn, or potatoes, with any kind of meat, or fish, or egg, or beans/lentils or nuts, ( Avoid pre-marinaded or grill-ready meats and fish because they often have gluten in the seasoning ), and any kind of fresh, frozen, or tinned vegetables, ( again watch out for additives, esp. hydrolysed veg protein, which is gluten, and modified starch which will be contaminated with gluten, unless it specifically says it is corn starch ).
To thicken sauces use corn or rice flour, or that seaweed stuff, forgotten what it's called, and use olive oil or duck fat or coconut or seed oils for fats rather than butter.
eg.
Brown/half brown rice served with red kidney beans cooked slowly in a tomato and garlic and olive oil and herb sauce until lovely and soft.
Egg fried rice with bits of meat, fish, vegetables.
Tuna mayonnaise with baked potatoes and salad.
Crisp taco corn shells with ground beef and kidney beans cooked in oil and spices with garnish of finely chopped green salad and tomato, salsa, and avocado mush/guacomala ( but no grated cheese or sour cream; use spiced/salted toasted sesame seeds and a cream made of tofu instead if you want to replace those things a bit ).
Duck or lamb or pork or steak with finely sliced courgettes ( "squash" in the USA? ) cooked fast/briefly in a herby garlicky tomato sauce, and rice if you wish.
Smoked salmon with scrambled egg and chives/dill or parsley. Salmon steaks/filets with broccoli and potatoes or rice.
Roast chicken with spicy red lentil sauce and rice
Duck breast ( "magret" ) with chestnut puree ( boil chestnuts till very soft in apple juice, then mash with a bit of rendered duck fat and/or olive oil, salt and pepper and a tad of honey to taste ) and a green salad.
... ... ... fish curry; ham and pea soup; moroccan tajines, ( meats gently stewed with dried fruit, or carrot and onions, and tomato, lemon, etc ) served on rice rather than couscous; big hot-pots of rich green cabbage, ham/bacon, ( beware bacon cured with wheat dextrose ), potato, carrot, swede, olive oil, etc; smoked dry ham and melon pieces; prawns with garlicky or lemony mayonnaise ( check the mayo ingredients or make your own ); mussels and chips/french fries and mayo; ... steak and salad ... huge summer salads like egg and potato and gherkin and herbs in a mayo/tofu/sesame seed puree dressing ...
There's too much choice, so many wonderful meals with no gluten or casein in ... I could go on for ever making suggestions.
Good luck with the cooking ... and bon appetit!
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