I almost never cook anything or make a brew during the day when I'm actually walking, I just can't be bothered, though lots of people do
Sometimes I use the expensive hiking meals; there are two types
Dried, where you add boiling water to the packet and let it soak; these are more properly known as Accelerated Freeze Dried, or AFD
Those where you boil a foil & plastic pouch, these are variously known as Wet Meals, Ready To Eat, Meals Ready To Eat, or their initials - RTE or MRE. As they contain the full water content they will be heavier than AFD
Their disadvantage is that both of them are expensive
For something cheaper and fairly quick & easy to cook & eat there are -
Canned food;
Pasta 'n' Sauce from various manufacturers; can extend these by adding, for example, a small can of tuna; about 1/2 a horseshoe shaped smoked pork sausage, chopped up
Make up your own meals from pasta, Textured Vegetable Protein (TVP), Savoury Rice, Beanfeast & similar products
Dried soup - could make a meal from dried soup plus oatcakes & cheese
Just browse round a big supermarket or a couple of bargain/discount stores and use your imagination
Vac packed frankfurter sausages; either in a sandwich, or make up instant noodles and chop them into it. This is possibly the quickest, easiest, and cheapest backpacking meal you can think of
Vesta dried meals are still on the market; cheaper, but take longer to cook
Vacuum packed bacon lasts reasonably well, and is easier to cook than sausages or burgers; canned Spam or Bacon Grill
Another alternative is soup, oatcakes & cheese, then stewed dried fruit; you could even add one of the many instant custard things
Instant mash and bacon or corned beef or canned bacon grill
To cook dried pasta type meals, you don't need to simmer all the time. Bring it to boil; let it soak for about 1/2 an hour or longer; then boil it up again The pan should have a lid to do this, both to conserve heat and keep the flies out. You could use a pot cosy as well, or drape it with your spare jersey. You will find that as you gain experience this just becomes a part of the routine
Wet meals and canned food can, if necessary, be eaten cold, as it is cooked & sterilised as part of the manufacturing process. Cold Irish Stew might not be very appetising, but it won't do you any harm
You can take semi-fresh or canned for the first night or two, then all dried after that
You will see that most hiking food is junk. When you're hiking you're more interested in bulk & stodge than fine dining & quality; but remember, you don't have to live off it forever
I never fry when I'm backpacking, but if you want to, get a small non-stick frying pan, either on its own or part of a set
Foe washing I use a small foam/scourer pad. I don't take washing up liquid, I just rub it on my bar of ordinary toilet soap - get some that's not too highly perfumed - cheap supermarket brand is as good as any
Like I said, I don't fry so that is all the soap I need
If you're wild camping you will be near a water source anyway. put a small amount of water into the pan, clean it, then empty it in some rough vegetation well out of the way. Do not pour it back into the stream!
If the stream water has been clean enough to drink, perhaps with tablets or filtration, it will be clean enough for washing. If you're bothered, do all the cleaning with that water, then rinse it with a very small amount of drinking water
If you're on a campsite there will be water available and usually a sink
Have a browse round YouTube for backpacking food, there are loads of videos, but remember that a lot of them are American; still it all helps to give you an idea