She is the chef and co-owner of the popular Italian restaurant Diva in Delhi, which she established in 2000, with co-founder Gita Bhalla under partnership firm "Riga Food".
In June 2016, Dalmia and five others, all members of the LGBT community themselves, filed a writ petition in the Supreme Court of India challenging Section 377 of the Indian Penal Code.
[7] This resulted in the 2018 landmark judgment in Navtej Singh Johar and others v. Union of India in which the Supreme Court unanimously declared the law unconstitutional "in so far as it criminalises consensual sexual conduct between adults of the same sex".
In 1993, at the age of 22, Dalmia started her first restaurant 'MezzaLuna' in the Hauz Khas Village, Delhi, that specialised in Mediterranean cuisine with an "Italian accent".
In 1996, Dalmia moved to London, where she opened the first Indian fine dining restaurant on King's Road, with partner Andy Verma.