Preheat an oven to 375°F.
Mince sage, rosemary, pepper, garlic, 1 teaspoon salt, 1/4 teaspoon black pepper, and fennel pollen together.
Heat a frying pan over medium-high heat. Add 1 tablespoon of oil. Cook pork for 10 minutes, turning occasionally until golden on all sides.
Roll the pork in herb mixture and set aside.
Cut baguette in half the long way and scoop out insides. Brush inside of baguette with remaining 3 tablespoons olive oil.
Place pork inside of baguette so pork is completely enclosed. Trim off excess ends of bread. Tie at 1 to 2-inch intervals with kitchen string.
Place pork on a baking sheet and roast at 150°F for 25 minutes.
Remove from oven, let rest 10 minutes.
Remove strings, cut into slices, and serve.