Put the potatoes in a large pot and cover with salted cold water. Cover and bring to a boil over high heat. Lower the heat and simmer until the potatoes are easily pierced with a fork, about 10 minutes. Drain in a colander.
In a very large bowl, whisk together the mayo, mustard, vinegar, agave, kala namak, and turmeric. Transfer the warm potatoes to the bowl and toss to coat in the dressing.
Fold in the carrot, celery, scallion, and tofu, along with several grinds of black pepper. Taste and adjust for salt and seasoning.
Cover tightly and refrigerate until ready to serve. Top with a light dusting of paprika and fresh dill before serving.
