Step 1

Cut each lemon rind into a few chunks and toss with salt in a large glass, ceramic, or stainless steel mixing bowl. Cover tightly with plastic wrap and place in refrigerator for 12 hours or overnight.

Step 2

Using a cheesecloth-lined or fine-mesh stainless steel strainer set over a nonreactive bowl, strain the liquid that has collected at the bottom of the bowl. Working in batches, transfer rinds to a stainless steel or plastic potato ricer and squeeze to release any extra liquid, allowing it to pass through strainer into bowl. (You can also twist the rinds in a doubled-over sheet of cheesecloth, wrapping the ends of the cheesecloth around a spoon for torque to help express the liquid; see our article on making latkes for photos and a fuller description of the technique.) Discard rinds and any salt left in the strainer.

Step 3

Scrape liquid and any solid salt in bottom of bowl into a small plastic or glass container; there should be about 1/2 cup (120ml) liquid. Submerge kombu in liquid, cover, and place in refrigerator for 12 hours or overnight.

Step 4

Remove kombu from liquid and place in a small saucepan along with 1/2 cup (120ml) water. Bring to a simmer over medium-high heat; do not allow to come to a boil. Once the mixture comes to a simmer, shut off the heat.

Step 5

When kombu dashi is cool, strain it into salt-lemon solution, stirring to dissolve any solid salt at the bottom of the container; discard kombu. Refrigerate tare for up to 2 months.