How to insert tab character when expandtab option is on in Vim

Question

When I\'m in insert mode and I have the expandtab option switched on, pressing Tab ↹ results in inserting the configured number of spaces.

But occasionally I

Answer 1

From the documentation on expandtab:

To insert a real tab when expandtab is on, use CTRL-V. See also :retab and ins-expandtab.
This option is reset when the paste option is set and restored when the paste option is reset.

So if you have a mapping for toggling the paste option, e.g.

set pastetoggle=

you could also do Tab.