In a bowl, combine all of the ingredients. Set aside.
Noodles and Vegetables
In a pot of boiling water, cook the soba noodles until al dente. Drain and toss with oil.
Meanwhile, in a large non-stick skillet over high heat, cook the cabbage in 1 tbsp (15 ml) of the oil for 5 minutes or until al dente. Lightly season with salt and pepper. Set aside on a large plate.
In the same skillet, cook the mushrooms, baby broccoli and carrot in the remaining oil for 5 minutes or until al dente. Lightly season with salt and pepper. Set aside with the cabbage.
In the same skillet over medium-high heat, heat the reserved sauce for 2 minutes. Add the vegetables and noodles. Toss well to coat in the sauce. Transfer to a serving dish and keep warm.
In a bowl, whisk the eggs, soy sauce and brown sugar. Season with salt and pepper.
In the same skillet used to cook the vegetables over medium-high heat, cook the egg mixture in the sesame oil, swirling the skillet from side to side to completely cover the bottom with the egg, until cooked through. Sprinkle with chives. Remove from the heat.
Using a spatula, unstick the edge of the omelette from the side of the skillet. Slide the omelette onto a work surface. Using your hands, roll up the omelette and cut into 4 equal pieces.
Serve the omelette over the soba noodles and vegetables.