- 2 cups finely chopped onions, divided
- 1 large egg
- 1 1/4 teaspoons coarse kosher salt
- 1/4 teaspoon freshly ground black pepper
- 2 pounds russet potatoes, peeled, cut into 1-inch pieces
- 1 tablespoon all purpose flour
- 1 teaspoon baking powder
- Vegetable oil (for frying)
- 6 tablespoons olive oil
- 2 tablespoons Sherry wine vinegar
- 1/4 teaspoon dry mustard
- 2 large bunches watercress, thick stems trimmed (about 8 cups)
- 1 large avocado, pitted, peeled, diced
- 4 ounces thinly sliced smoked salmon, cut into strips
- Line colander with kitchen towel. Stir 1 1/2 cups onions, egg, salt, and pepper in large bowl. Place remaining 1/2 cup onions in processor; add potatoes. Blend until potatoes are very finely chopped and some of mixture is pureed; transfer to prepared colander. Wrap towel around potatoes, squeezing out as much liquid as possible. Scrape into bowl with egg mixture. Stir in all purpose flour and baking powder.
- Heat 4 tablespoons vegetable oil in heavy large skillet over medium-high heat. Drop potato mixture by scant 1/4 cupfuls into skillet; flatten each latke to 2 1/2-inch round with metal spatula. Reduce heat to medium. Cook until golden, about 4 minutes per side. Transfer to large rimmed baking sheet. Repeat, adding more oil to skillet as needed. DO AHEAD: Latkes can be made 2 hours ahead. Let stand at room temperature.
- Preheat oven to 425°F. Bake latkes until crisp and deep brown, about 6 minutes per side.
- Whisk oil, vinegar, and dry mustard in small bowl to blend. Season with salt and pepper. Combine watercress, avocado, and salmon in large bowl. Toss with enough dressing to coat.
- Arrange 2 latkes on each plate. Mound salad alongside.
- Bubbles. Louis Bouillot “Perle d'Aurore” Crémant de Bourgogne Rosé (France, $17) will taste great with the latkes and everything in the salad.