The Sastra says " agniShomIyAtmakam idam jagat " i.e, the entire Creation is a combination of Agni (fire) and Soma (Moon).
Agni is the Bhokta (enjoyer in the form of Pitru-sakti) and Soma is the Bhojya (in the form of stri dharma). The Soma derives its bhojya dharma from Agni which is Bhokta.
It is this Soma tattva which is responsible for Nourishment in the form of Anna (Food), Medicinal Plants, and Sapta (7) Dhatu Vriddhi.
The Shakta Tantra (Annadakalpa Tantra) extols this Agni to be Siva and Soma to be Annapurna. There is an esoteric essence in Annadakalpa Tantra where the Divine Pair Siva & Annapurna denote the " AgniShomIyAtmaka tattva " ie., Agni & Soma where Siva is the Dharmi and
Annapurna is the Dharma.
To denote the nourishing attribute of Soma in Annapurna, She is contemplated as holding a pot of porridge in one hand and serving the same with affection with other hand to Her children.
Annadakalpa Tantra takes the reader to the lofty heights of devotion towards Mother Annapurna and details out Her dhyana murti (tamasika, rajasika & sattvika), Her avarana archana, Her Mula Vidyas of Sapthadasakshari & Ashtadashakshari Vidya, the Diksha & Purascharana Vidhana,
the Adhikara Nirnaya in Annapurna Upasana, Annapurna Kavacha etc.
bhikShAm dEhi kripAvalambanakari mAtA annapurnEShwari....