In a blender, combine the vinegar, lemon juice and shallot and puree. With the machine on, add the olive oil and canola oil and puree until emulsified. Season the dressing with salt and pepper.
In a large bowl, toss the greens with the endives, cucumber, tomatoes, dill, olives and feta. Add half of the dressing, season with salt and pepper and toss. Add the remaining dressing, toss again and serve.
Make Ahead The dressing can be refrigerated overnight.