Rinse the dried sea vegetables. Rinse several times if you prefer less of an 'ocean' taste.
Place them in a small pot of cold water and bring to a boil.
Simmer for 10 minutes, then remove pot from heat and let stand, covered for 30 minutes or longer until the arame and hijiki re-hydrate and become tender.
Drain sea vegetables well (retain cooking water as a soup stock).