Soak the wakame in iced water for 45 minutes. Drain in a sieve, pressing to remove any excess liquid.
Thinly slice into strips and add to a bowl with the onion, capers, soy sauce, vinegar, sesame oil and garlic. Stir to combine.
Put the chopped avocado, olive oil and lemon juice in a bowl. Mash well with a fork, then season.
Using a mortar and pestle, grind the white sesame seeds and ½ tsp salt to a powder.
Spoon the guacamole onto a large plate, top with the seaweed pesto and sprinkle over the sesame salt. Garnish with black and white sesame seeds and a few micro herbs, if using. Serve with crackers on the side.