Step 1In a medium bowl, sprinkle the yeast over the warm water and stir to dissolve. Stir in 1 cup of the flour until smooth. Cover and let stand 1 hour.
Step 2Transfer the yeast mixture into a large mixing bowl and stir in 2 tablespoons of the olive oil, 3 tablespoons of the sugar, one-half teaspoon of the fennel seeds, one-half teaspoon of the rosemary, the orange zest and the salt. With a fork, beat in 1 cup of the flour until blended. Beat in the remaining 1 cup flour. On a lightly floured board, knead the dough for 5 minutes until smooth and satiny.
Step 3Place the dough into a large bowl lightly coated with 1 teaspoon olive oil and turn to coat all sides of the dough. Cover and let rise in a warm place until doubled, about 1 hour. Punch down the dough and knead lightly for a minute, then pull and shape into a 16-by-9-inch rectangle on a baking sheet.
Step 4In a small pan, heat 1 teaspoon of the chopped rosemary in the remaining 1 tablespoon olive oil over low heat just until warm. Brush the top of the dough with it. Let the dough rise until puffy and doubled, about 30 minutes.
Step 5Meanwhile, heat the oven to 375 degrees. Wash the grapes and pat them dry. You can either remove the seeds from the grapes or leave them intact. They can be removed quite easily without cutting the grapes in half: Insert the tip of a small knife into the stem end of the grape and lift out the seed. Toss the grapes with the remaining 2 tablespoons sugar and let stand while the dough is rising.
Step 6Using your fingers, make random indentations to cover the entire surface of the bread, as with focaccia. Gently press the grapes into the indentations to keep them in place. Sprinkle the top of the bread with the remaining 1 teaspoon fennel. Bake 30 to 35 minutes until browned and the grapes have popped open. Remove from the oven to a wooden board to cut into serving-size pieces.