In Jain dharma, potatoes and onions are generally avoided.

• Potato is a root vegetable, and Jainism avoids root vegetables because uprooting them can harm many living beings in the soil and the plant is destroyed.
• Onion is also avoided in strict Jain diet, especially because it is a root vegetable and is considered to increase passion and disturb spiritual discipline.

So, for a Jain diet, both potato and onion are not recommended.