There's lots of ways to make chives vinegar.
1) use white wine or apple cider vinegar, and as many chives flowers (Allium schoenoprasum) as will fit your vinegar. Let sit for 7-14 days in a shady spot. You'll get a faded-pink vinegar. The taste is of onion with a hint of sweetness: chives flowers contain nectar.
2) use diluted white (industrial) vinegar. Ours is 10 % and should be diluted 2:3, that is, 2 parts vinegar to 3 parts water. Put as many chives flowers as will fit into your jar and cover with the water-vinegar mixture. Let sit in a shady spot for 7-14 days. You'll get a shocking pink vinegar.
Pic: The colors of chives flower vinegars.
There's always ants and spiders in chives flowers. They'll end up floating around the bottom of your jar, but they'll get strained out when you strain out the flowers, after 1-2 weeks.
Keep your chives flower vinegar in the dark while it brews, and after you've strained it, too. The colors will fade in light.
This'll make a dandy cleaner for your bathroom tiles if you don't like the taste, although lavender or rose vinegars are nicer, for the short while that the scent lingers.
Related entry: Rose petal vinegar