Meanwhile, mix mayonnaise and sriracha; set aside 3 tablespoons of the sriracha mayo for the dressing. Mix dulse flakes, ginger, soy, vinegar, sesame oil, and agave into the remaining mayo mixture.
Pulse chickpeas in a food processor until it is a mix of coarsely and finely chopped. Turn into a medium bowl and add the mayonnaise mixture, along with the scallions and celery; toss to combine. Refrigerate to set up and chill while preparing the vegetables and avocados.
To serve, spoon a portion of rice and the chickpea mixture into each of 4 to 6 bowls. Arrange vegetables and avocado over each bowl. Sprinkle with sesame seeds and scallions, drizzle with sriracha mayo dressing, and serve.