Harry Bloomfield wrote:
After serious thinking F wrote :
I've got most of the grease/grime off a tiled kitchen (not ours, I
hasten to add!) but the grout is in pretty poor condition with
grease and food/spices staining it.

Anyone able to suggest an easy/quick (probably mutually exclusive
but I can dream!) way to get the grout back to how it was?

Get a tile grout scraping out tool, scrape it out and regrout it?

Seconded. For "grout scraping out tool" read suitably sized flat bladed
screwdriver used edge on. Done many this way over the years.