A Slashy Dashy Spiral
Charcoal, 17 16 bytes:

↶⁴-Ｆ⊖Ｎ«↶²/ι↶²\-ι


Try it online! Link is to verbose version of code.

↷²-¶Ｆ⊖Ｎ«/ι↶²\-ι↶


Try it online! Link is to verbose version of code.

Edit: Saved 1 byte thanks to @icrieverytim.