To make the nanbanzuke sauce: combine the dashi stock, soy sauce, rice vinegar, sugar, and lemon juice in a large bowl and mix well. Add salt to taste
Remove any stringy parts from the celery and chop it and the carrots into 2 inch julienne strips . Cut the ginger into thin matchsticks. Carefully remove the seeds from the chili and slice finely into small rings. Finely slice the onion
Prepare the salmon by cutting into 1 1/2 inch square pieces. Season with a little salt and pepper and dust with flour
Heat enough oil to cover the salmon in a heavy saucepan and when it is very hot, deep-fry the salmon
When just cooked and crispy, remove the salmon from the pan with a slotted spoon to drain off any excess oil and place in the nanbanzuke sauce to marinate. This should be done while still hot so the salmon absorbs the rich flavors of the sauce
Add the celery, carrot, ginger, chili, onion, and sliced lime to the salmon, cover and marinate for a minimum of 30 minutes
To serve, pile a little of the celery, carrot, ginger, chili, onion, and sliced lime on top of each salmon piece