I've recently started commuting on bicycle again after a two or three year hiatus. The new commute is 12 miles each way instead of 3, but back then I used to take a 30 mile detour two or three times a week. I've noticed a big change since I was 24, which is that I can't just have a sip of water, go ride 30 miles, and be ready for a nice lunch... Now I actually seem to require some kind of sustenance before I go!
For the most part, I have been making smoothies for my morning fuel (supplemented by a double-shot of espresso a third of the way into the ride). The base is banana, soy yogurt, cashew butter, soy or almond milk, and cocoa powder from Trader Joes. The last two days, I have also thrown in an apple, and ended up with a very thick, pudding-like smoothie which tastes great and keeps me going through the bike ride all the way until lunchtime.