I get grumpy the hungrier I get, to the point where I'm unable to function and it's pretty unpleasant. So I like to have things floating around for me to emergency snack on, and these Be Natural muesli bars have become my favourite, especially for flights and, as it turns out, single bite snacks whilst engaging in sports.
Not all of them are vegan, but about half of them are (none of the chocolate ones, sadly!). My favourite is the purple one pictured here, which contains pepitas, currents, berries, and some kind of nut.
These are available in my local supermarket, which makes them easy to find!