For regular day to day meals, we generally want higher-fibre slow-digesting carbohydrates such as
1. starchy tubers such as potatoes, and sweet potatoes
2. fruit
3. beans and legumes
4. whole grains
5. higher fibre versions of bread, pasta etc (eg sprouted bread, bean pasta)
And of course we want to eat normally most of the time, including before and after training.
For intra-workout nutrition we want faster-digesting carbohydrates. This is especially true if we're drinking them in a shake or solution.
For this purpose you can still use whole foods, or supplements. But not everyone will need these!
Whole-food options
If you have a blender and want to use whole foods for intra-workout nutrition, try blending (along with protein);
banana or cooked plantain
other fruits
cooked white or sweet potatoes
soaked rolled oats
One study found that raisins are just as effective as 'sport jelly beans'!