In a small heatproof bowl, whisk together the boiling water, sugar and salt until the sugar and salt are dissolved. Stir in the rice vinegar, radishes and chilies. Let sit for at least 10 minutes.
In a large bowl, toss the rice, 1 tbsp of the grapeseed oil, and salt to mix. In a large nonstick skillet, heat 2 tbsp of the grapeseed oil over medium heat. Once the oil is hot, drop a couple of grains of rice into it. If it sizzles, it’s good to go; if it doesn’t, heat the oil longer. Scatter the rice into the pan (set aside the bowl) and cook, undisturbed, until golden brown on the bottom, 6 to 8 minutes. Using a flexible spatula, flip the rice in sections and cook, undisturbed, until the other side is golden brown, about 6 minutes. Remove from the heat.
Meanwhile, trim the ends off the cucumbers. Place the flat side of your knife over each cucumber and press down with the palm of your hand until the cucumber breaks open. Tear the cucumbers into bite size pieces and transfer to the large bowl (no need to wipe it clean). Add the bok choy.
Pour ⅓ cup of the pickling brine into a small bowl, using a fork to hold back the radishes and chilies. Stir in the tamari, lime juice, and the remaining 1 tbsp grapeseed oil.
Transfer the crispy rice to a large serving platter. Drizzle 2 tbsp of the dressing over the cucumbers and bok choy, toss to coat and scatter over the rice. Scoop the radish out of the pickling brine and scatter them over the dish. Top with the Thai basil, cilantro, smoked tofu (if using) and peanuts. Serve with lime wedges and a small bowl of the pickling brine and chilies for drizzling (if you like things spicy).