Preheat the oven to 425*F/218*C.
While the oven is heating, cut the top off the eggplant, then slice into pieces about 1/2"/1.27cm thick. You can cut the eggplant into thick strips, or you can slice it into steaks- just make sure the thickest part of the eggplant is no more than 1/2"/1.27cm thick.
Lay the eggplant pieces on a sheet pan lined with parchment paper or aluminum foil.
Lightly sprinkle the eggplant with salt, then set aside while you make the dressing.
In a small bowl, combine the miso paste, tahini paste, sugar and lime. Use a fork or a small whisk to mix well; there likely will be lumps. Add the hot water a little at a time, whisking in between each addition, until the dressing is smooth. You may not need to use all the water.
Brush the tops of the eggplant lightly with the dressing, reserving the rest. Place the eggplant in the oven and roast for 5 minutes.
Remove the eggplant from the oven and brush with the remaining dressing. Place back in the oven and roast a further 5-8 minutes, until the eggplant is completely soft all the way through.
Remove and sprinkle with sesame seeds. Serve warm.