How to Make It
Toss together cabbage, 1/4 cup oil, 2 tablespoons vinegar, 11/2 teaspoons kosher salt, and 1/2 teaspoon pepper in a large bowl; set aside.
Stir together fromage blanc, scallion, garlic, 1 tablespoon oil, remaining 1 teaspoon vinegar, remaining 1/2 teaspoon salt, and remaining 1/4 teaspoon pepper in a small bowl; set aside.
Melt 1 tablespoon butter with 1 tablespoon oil in a large skillet over medium. Add baguette slices; cook, undisturbed, until golden on bottom, 4 to 5 minutes. Add remaining 1 tablespoon butter and remaining 1 tablespoon oil. Flip bread. Cook, pressing with a spatula to flatten, until crisp on bottom, 4 to 5 minutes. Sprinkle evenly with sea salt, pink peppercorns, and fennel seeds.
Spoon about 2 1/2 tablespoons fromage blanc mixture on each of 6 plates. Top evenly with cabbage mixture, apples, and toasted baguette slices. Garnish with sorrel leaves, if desired.