Is it better to read the Qur’an frequently during Ramadan or to be preoccupied with preparing food? And is one sinful if they become angry due to a lack of help with housework?

The acts you perform after prayer, such as reciting the Quran and then preparing food for your family, will earn you more reward than your sister, because the Prophet, peace and blessings be upon him, said: "Today, those who broke their fast have taken the reward," and "The most beloved of people to Allah Almighty are those who are most beneficial to people." Do not be angry with your sister, and rejoice in the reward stored up for you. There is no sin upon you in asking her for help.