A useful leftover bowl starts with food that was stored safely. Sauce and a hot pan cannot rescue rice that spent too long at room temperature.
Use promptly chilled rice within the storage guidance you follow; the UK Food Standards Agency advises refrigerating rice quickly and using it within 24 hours. Reheat only the amount you will eat, until steaming hot throughout, and do not reheat it repeatedly.
Warm leftover cooked beans and vegetables thoroughly in a pan with a little water. Heat the rice separately if that makes it easier to check the center. Assemble with fresh cucumber, chopped herbs, and a dressing you already enjoy, such as lemon tahini or a little soy and lime.
Keep the contrast deliberate: a warm base, hot cooked additions, and a small fresh topping. Mixing everything into a pan from the beginning often sacrifices the fresh part without improving the reheating of the rest.
Further reading: Food Standards Agency: student food-safety guide.