Use a sharp knife to mince the salmon fillet down to a fine paste. In a medium-sized bowl mix the salmon, shallot, ponzu vinegar, olive oil, ichimi chilli and egg yolk with a fork to evenly incorporate all the ingredients.
Carefully spread the salmon mixture across two-thirds of a serving dish. Slice the avocado and squeeze over the lemon juice to prevent the avocado from going brown. Place this beside the salmon on your dish. Fill the remaining section of your tray with salmon caviar.
Serve with crackers and a spoon.