I will be working in a kitchen for the next few months and I'm in need of some decent slip-resistant shoes. They have to be black or dark gray. If possible, I would prefer a pair that isn't too expensive, as I'm only going to use them for a short time. What do you recommend?
Try cork footwear. Cork is good for your feet as you will be standing most of the time. Cork has good grip and you will not slip in such shoes. Colour Me Mad has cork shoes which are black in colour. https://colourmemad.com/index.php/loafee-navy-blue-zigzag.html
I wear Timberland Madison Summits most the time. I'm not sure you can get them in black though, nor are they the cheapest around. But you sure won't slip in them, and they still look sharp. Sometimes I wish they looked a little less sharp so I could use them for yard work or shovelling because they are so sturdy.