Purple Pea Water

The toehr night I had quite the shock when I took the steamer off the top of the potatoes!

 It was like I was cooking them in ink! 

Above the potatoes I was steaming both Victorian Purple podded peas (but as mange tout) and some broad bean tops (easily one of the most underrated veg out there), both of which must have imparted some of their colour into the water. 

I used to work with a Bulgarian guy who used to moan about how the English cook. 

He used to ask "Why do you chuck the water away? All the Goodness there." 

Then he'd eat the water from his boiled runner beans like a soup as a starter. I think he was probably on to something. 

Other than making gravy from this water though I'm not sure what else to do with it? I suppose it could be saved as a light stock for a soup? 

Do you save the cooking liquid from things you cook?