Place kombu in a saucepan and cover with water. Bring to a boil. Reduce heat to medium-low, cover, and simmer until kombu has softened, about 5 minutes. Drain and cool until easily handled, 5 to 10 minutes. Slice rehydrated kombu into thin strips.
Whisk honey, soy sauce, ginger, and rice vinegar together in a large bowl. Add kombu, carrots, cucumbers, and sesame seeds; toss to combine. Let sit in the refrigerator until flavors combine, 10 to 15 minutes.