Fill a large bowl with ice water and set aside. In a nonreactive medium bowl, add the shallots, separating them with your fingers. Add 2 tbsp. vinegar and toss to coat; refrigerate.
In a large pot of boiling, salting water, cook the green beans until crisp-tender, 2 to 3 minutes. Drain in a colander, then transfer the colander immediately to the ice bath, stirring the beans gently to encourage even cooling.
In another bowl, whisk together the remaining 2 tbsp. vinegar, the paprika, Worcestershire and mustard; season with salt. Slowly drizzle in the EVOO, whisking constantly to thicken.
Drain the beans and transfer to a towel; pat dry. Transfer to a serving bowl. Add the shallots, discarding the liquid. Pour in the vinaigrette and toss to coat. Serve immediately.