Preheat oven to 350°F (175°C).
Heat 1 teaspoon of neutral oil in the small saucepan. Add the chopped onion and cook on medium-low heat for 5 to 7 minutes, until onion is clear.
Add the tamari sauce, honey, rice wine vinegar, and grated ginger, and bring to a simmer. Cook for about 5 minutes, until thick and syrupy. Set aside.
In a large nonstick skillet, heat 2 tablespoons sesame oil over medium-high heat. Cut the baby bok choy in half lengthwise, and add them, cut side down, in the skillet. Cook for 2 to 3 minutes, until the cut sides of the bok choy, are golden brown.
Add the water and soy sauce, and continue cooking until dark green leaves are wilted, and the white parts are tender. The bok choy should remain cut side down throughout the process.
Meanwhile, heat the remaining 2 teaspoons neutral oil in a medium nonstick skillet. Cut the lamb loin into four 2-inch thick medallions, pat dry, and season liberally with freshly ground pepper. Add to the skillet, and cook for 2 to 3 minutes per side until nicely browned. While the second side is cooking, brush the top side of the lamb loins with the tamari-honey glaze. Brush it twice to make sure there is a thick coating. Set the skillet into the oven and cook for five minutes. Remove the skillet, and brush again with the tamari-honey glaze,
To serve, place 3 halves of bok choy on each plate, and 2 lamb loin medallions. Sprinkle everything with togarashi and white sesame seeds. Serve immediately.