@Isthiscorrect
I usually use my food processor to chop the onions and garlic really small and cook them in oil slowly for ten minutes- say one onion and two cloves of garlic. It also helps if you have a blender wand if you like smooth soup. Otherwise you could leave it as a broth but maybe chop the veg smaller.
If you don't have one you could just chop by hand and cook the onion first then add the garlic for the last two minutes.
Then you need some stock or a stock cube dissolved in a pint or so of boiling water.
You can use so many different veg, a just a few ideas:
Pea soup - chuck a load of frozen peas in, cover with stock (probably 30% more water than if you were just cooking peas - you can always add more as you go or at the end if you end up with a mass of solid pea! You can add more water but not take away if you have put in too much). Bring to the boil and simmer for 5 minutes - you still want the peas to look bright green. Whizz up with wand, bring back to the boil/simmer for a few minutes, salt and pepper, you could even put some ham or bacon in.
Vegetable soup - Two carrots and one potato work quite well or those stew packs you can get from supermarkets that come with swede as well. This one takes about 20 minutes to boil/simmer then whizz up, season and bring back to boil/simmer briefly. May need more water/stock depending on how much veg you put in- again, more than if you were boiling potatoes to make mash. One big potato and two carrots amazingly makes about four portions. Amazing with crisped up streaky bacon bits on top.
Tomato soup - Same process but with tin of chopped tomatoes, I usually put a bit of basil in at the end. Peppers very nice too, can chop and fry them at the beginning with the onions. I usually add a bit of ketchup as well. Less stock/water is required here, probably half a pint. Take about ten minutes to cook- could probably cook it for longer but I'm too impatient, hungry. Whizz up, season etc and it definitely needs grated cheese on top.