Preheat the oven to 375°.
Trim tough outer leaves from fennel; reserve fennel fronds for garnish, if desired. Remove and discard stalks. Cut fennel bulbs in half lengthwise; discard core. Cut bulb halves in half lengthwise.
Arrange potatoes in a single layer in a jelly roll pan or large roasting pan coated with cooking spray; drizzle with oil. Remove white papery skin from garlic head. Separate and peel cloves. Finely chop 1 garlic clove; sprinkle over potatoes. Add peeled garlic cloves, pepper strips, fennel seeds, coriander, paprika, salt, and black pepper to potatoes; toss well to combine.
Heat broth in a small saucepan over medium heat until warm. Remove from heat; stir in saffron. Let stand 10 minutes. Stir in vinegar; drizzle broth mixture over potato mixture. Bake at 375° for 30 minutes. Remove from oven, and arrange fennel wedges over potato mixture. Return to oven; cook an additional 50 minutes or until the broth mixture almost evaporates and potatoes begin to brown, stirring once. Garnish with reserved fennel fronds, if desired.