Although the name tartine often refers to a French open-faced sandwich, this version is closer to Italian focaccia topped with piquant salad. Because it's inexpensive to make your own flatbread, you can splurge on real Italian Parmigiano-Reggiano, which makes a huge difference in a simple recipe like this one. You'll also have room in the budget for 2 ounces thinly sliced prosciutto for a salty, savory note.
1/2 cup warm water (100° to 110°)
1 teaspoon sugar
1 package dry yeast
5.6 ounces all-purpose flour (about 1 1/4 cups)
3 tablespoons olive oil, divided
5/8 teaspoon kosher salt, divided
1/4 teaspoon black pepper
1/2 cup coarsely chopped walnuts
1/3 cup very thinly sliced red onion
1 teaspoon chopped fresh thyme
2 cups arugula
1 teaspoon fresh lemon juice
2 ounces thinly sliced imported prosciutto
1 ounce fresh Parmigiano-Reggiano cheese, shaved
How to Make It
Preheat oven to 450°.
Combine the first 3 ingredients in a medium bowl, and let stand for 5 minutes or until bubbly. Weigh or lightly spoon 6 ounces flour (about 1 1/4 cups) into dry measuring cups, and level with a knife. Stir 4 teaspoons olive oil into yeast mixture. Add flour, 1/4 teaspoon salt, and 1/4 teaspoon black pepper to yeast mixture, stirring until a soft dough forms. Knead dough on a lightly floured surface until smooth and elastic (dough will be soft and tacky).
Place dough in a large bowl coated with cooking spray, turning to coat top. Cover and let rise in a warm place (85°), free from drafts, 45 minutes or until doubled in size. Punch dough down; cover and let rest 5 minutes.
Drizzle 2 teaspoons oil into an 11 x 7inch glass or ceramic baking dish. Press dough into dish. Cover loosely with plastic wrap, and let rise in a warm place (85°), free from drafts, 30 minutes or until puffy; sprinkle dough with 1/4 teaspoon salt, nuts, onion, and thyme. Bake at 450° for 18 minutes or until golden.
Place arugula in a bowl; drizzle with remaining 1 tablespoon oil and juice. Toss. Turn bread out onto a work surface; top evenly with prosciutto. Slice bread into 4 (2 3/4 x 7inch) rectangles. Top each serving with about 1/2 cup arugula mixture; sprinkle evenly with remaining 1/8 teaspoon salt. Top with cheese.