Our object of worship is the Gohonzon. The Gohonzon embodies the life of Nichiren Daishonin and the altar is the Buddha’s home.
If you eat rice, you may offer it to the Gohonzon. This, unlike water, should not be left all day. After the rice is cooked, the first portion should be offered to the Gohonzon. When offering the rice, please say this silent prayer:
“I offer deepest gratitude to the Three Treasures of the Buddhism of Sowing. Nam-Myoho-Renge-Kyo.”
Then, you may ring the bell three times and chant Daimoku (Nam-Myoho-Renge-Kyo) three times. Then remove the rice. Ringing the bell three times signifies appreciation for the Three Treasures.
You may also offer other kinds of food to the Gohonzon. A proper food offering would be vegetarian, being careful to avoid odiferous foods such as onions or garlic. When making offerings to the Gohonzon, ring the bell three times and chant Daimoku (Nam-Myoho-Renge-Kyo) three times.
Reference: Receiving the Gohonzon and Setting Up Your Altar, Nichiren Shoshu Monthly Magazine, November, 1998; The Basics of Practice book.