In Jainism, dietary practices are guided by the principle of ahimsa (non-violence), and many Jains follow a strict vegetarian diet. During special religious periods such as Paryushan or Paryushan Parva (which might be what you referred to as "party's Han"), even stricter food restrictions are observed.

Tomato: Many traditional Jain followers avoid eating root vegetables (like potatoes, garlic, onions, etc.) during Paryushan, but tomato is a fruit (technically, even though it's used as a vegetable in cooking) and is generally permitted. However, some stricter sects or individuals may avoid foods with lots of seeds, which includes tomatoes. It's best to check with your family's or community's specific tradition.

Lemon: Lemon is also generally permitted, as it is a fruit and does not involve uprooting the plant. However, during Paryushan, some Jains may avoid sour or spicy foods, so lemon may be avoided for personal or community reasons.

Conclusion: If you are observing Paryushan or another Jain festival with dietary restrictions, it's always best to check with your local Jain community or elders, as practices can vary. Generally, both tomato and lemon are permissible for most Jains, but stricter sects or during Paryushan may choose to avoid them. Always follow the guidance of your tradition or guru.