Don't try to wash it, just use soft cat litter / oil dry ( dry clay ) , grind it into the surface then leave it there. The fine powder will wick oil out of the concrete, when it turns oil colored, scrape it up and apply more. However, the soot may be more difficult and may or may not come up for a while.

And, since the clay is more or less concrete color it will hide much of the mess while it is working.