Dashi is foundational to Japanese cooking. There are numerous variations, but the standard is made by steeping kelp and the fine shavings of a specially processed loin of skipjack tuna. It's common to make dashi in 2 parts. The first, known as ichiban dashi, uses fresh ingredients, and yields a cleaner, more delicate broth. The second dashi is made by re-steeping the ingredients from the first, and adding some fresh katsuobushi. The measurements aren't extremely important, as flavor can vary depending on the specific product used. The point here is to balance the 2 flavoring elements against each other.