Practice!
My bike club has a weekly breakfast ride. We take a long route (20-25 miles) to a restaurant, sit down and eat (about an hour); then ride back to our starting point (5-12 miles).
The first time I did this it felt like I had concrete in my gut and legs on the post-breakfast return.
The first time we filled up with a heavy Mexican breakfast, the coffee and salsa had a violent interaction 5 miles away from the restaurant.
The next Mexican breakfast the violent reaction was 7 miles away.
Eventually I got used to it. No more reactions and good energy levels.
I try get lots of coffee, water, and a small OJ (electrolytes/sugar). Sometimes it's a light meal, sometimes it's heavier. Mostly carbs, I try to keep it low fat.
Whole-wheat French toast (no butter or sugar); 2-egg omelets and hash browns and toast; fancy oatmeal with fruit and yogurt; mexican eggs w/ beans and potatoes and tortillas; that sort of meal.
While we have different destinations each week, the last 4-5 miles of the return is almost always on the same route. I ride it like it was a time trial going as fast as I can.