It's true that simply by cooking and eating, in the right consciousness, one can make spiritual advancement. How does one go about cooking and eating in the right consciousness? First of all, we need to analyze the purpose behind our cooking. Are we cooking simply to fill our bellies or are we cooking to nourish our soul and the souls of others? This analysis will determine what our consciousness is and how the food we prepare will impact us and those who partake of our preparations.
Within many branches of the Hindu tradition, it is recommended that we remain mindful or consciousness of the physical and emotional suffering caused to others as a result of our food choices. A meat diet, which includes fish and eggs, is prohibited because the understanding is that any food that caused others to suffer will create a certain callousness in our minds toward the suffering of others. This callousness can restrict one's spiritual advancement.
In addition to being conscious of food types, the Vaisnava tradition suggests that we shift our consciousness in terms of who the food is being cooked for. Vaisnavism suggests that while one is cooking, they meditate on cooking for the pleasure of Krishna or Vishnu. Cooking for the pleasure of God is one way to purge our consciousness of selfishness. The food can then be offered to Krishna or Vishnu, in a mood of devotion and prayer.
Food that has been cooked in this consciousness and which has become sanctified by the simple offering process purifies the mind of anger, greed, pride and envy and helps us to connect our existence with the Divine. This connecting with the Divine through the process of cooking and eating is called Bhakti Yoga.