3 pounds medium red onions
2 Tbsp olive oil
1 teaspoon mustard
2 teaspoons minced shallot
1 teaspoon salt
1 Tbsp minced rosemary
3 Tbsp cider vinegar
1/2 cup olive oil
Peel the onions, then cut in half from root to top. Slice the halves into thick wedges, making sure to keep some of the root end attached; this will help keep the onion wedges from completely falling apart on the grill.
Coat the onions in the 2 tablespoons olive oil and some salt.
Prepare your grill for high, direct heat. Grill the onion wedges on each side until you get nice grill marks, about 3-5 minutes per side, depending on how hot your grill is.
After you’ve achieved grill marks on the second side of each onion wedge, turn the grill down to medium-low (or move some of the coals away from the grill grate), cover and roast for 15-20 minutes to soften the centers of the onions.
While the onions are cooking, make the dressing. Put the mustard, minced shallot, garlic, salt, rosemary, and vinegar in the bowl of a blender, and purée for several seconds.
With the blender on a low speed, drizzle in the olive oil until the dressing is emulsified.
Once the onions are cooked, remove the onions from the grill and slice off and discard any tough little root ends, and any outer skins that have become too dried out by the grill.
Toss the onions with the dressing and allow to marinate for at least 30 minutes before serving.
The salad improves with time, as the dressing flavors blend and penetrate the onions. Great to make ahead. Will last several days chilled.