Cook the noodles in plenty of rapidly simmering water until al dente, then drain.
Meanwhile, heat the oil in a small skillet. Add the garlic and sauté over low heat for 2 to 3 minutes, or until golden.
Transfer the oil and garlic to the container of a food processor and combine with the stock, peanut butter, cilantro, ginger, agave, hot sauce, and salt. Process until completely smooth.
In a small saucepan or skillet, combine the zucchini, tomatoes, and scallions with a small amount of water, just enough to keep moist. Cover and steam until the zucchini is just tender-crisp and the tomato has softened, about 3 to 4 minutes.
Combine the noodles with the sauce in a large serving bowl and stir until evenly coated.
Serve at once or allow to cool to room temperature, topping each serving with the a small amount each of the zucchini-tomato mixture, as well as either or both the optional cilantro and optional peanuts.