Slice zucchini into quarters lengthwise and trim away any seedy flesh. Cut each quarter into small 1/2 inch pieces. Place cut zucchini in a colander, sprinkle with about 1/2 teaspoon salt, and set over a sink for at least 15 minutes so zucchini can release some moisture.
Grill corn and poblano pepper until lightly charred. Remove from grill and let cool slightly
Pat zucchini dry with a paper towel, and place it in a large mixing bowl.
Cut kernels from corn, and cut poblano into 1/2-inch pieces.
Add corn, poblano pepper, cooked quinoa, tomatoes, scallions and cilantro to the zucchini and toss well to combine.
Add dressing about 30 minutes before serving, and toss well to combine.
Serve warm, room temperature or refrigerated.