To prepare the vinaigrette dressing, whisk together vinegar, shallot, mustard, oregano and sugar in a wide, shallow dish. 

Gradually drizzle in olive oil, whisking constantly until combined and slightly thickened. 

Season with salt and pepper. 

Transfer half of the dressing to a small bowl and set aside, then add tempeh to remaining dressing in dish, toss well, cover and chill for 30 to 60 minutes.

Meanwhile, place potatoes in a medium pot, cover with salted water and bring to a boil. 

Reduce heat to medium low and simmer until tender, 12 to 15 minutes; drain and set aside to let cool. 

Bring a large pot of salted water to a boil, add green beans and cook until just tender, 3 to 4 minutes; rinse in cold water and drain well.

Preheat the oven to 375°F. 

Arrange tempeh on a baking sheet in a single layer and bake, tossing halfway through, until golden brown, 15 to 20 minutes. 

Let cool slightly and then toss with reserved dressing, olives, tomatoes and capers.

To serve, divide greens, potatoes and green beans among plates, top with tempeh mixture and parsley and serve.