Bring a large pot of lightly salted water to a boil. Add soba noodles and cook for 6 to 8 minutes, until al dente. Drain and rinse with a little cool water to stop the cooking. The noodles should remain warm.
Meanwhile, heat olive oil in a large frypan over medium-high heat. Place scallops into the hot frypan and cook until golden brown without moving them in the pan, about 1 minute. Turn the scallops over and cook until golden brown on the other side, 1 minute more. Remove from the pan and set aside.
Stir in the minced garlic and cook until garlic begins to turn golden brown, about 30 seconds. Add the tomatoes, capsicum and basil. Cook and stir until the peppers soften and the tomatoes begin to release their juices. Stir in the Kalamata olives, Dijon mustard and reserved scallops. Season with salt and simmer over medium-low heat for 1 minute to allow the flavours to infuse. Place warm noodles onto serving plates and top with scallop mixture to serve.