Cold enough lately that I've actually started thinking about what goes in the flask rather than just chucking whatever's left in the pot.
I tend to default to builder's tea — strong, two sugars, no messing about. But I've had a thermos of decent coffee on a canal walk before and that was genuinely revelatory, I'll admit.
So what's everyone working with? Tea, coffee, something more adventurous? And does anyone actually have a flask they'd recommend — because mine's starting to taste of every previous brew it's ever held, which isn't ideal.