1 tablespoon coriander seeds
2 teaspoons cumin seeds
2 teaspoons dried oregano
1 tablespoon fennel seeds
1/2 teaspoon crushed red pepper
1/2 teaspoon salt
1/2 teaspoon whole black peppercorns
1 clove garlic
2 tablespoons olive oil, divided
1 medium sugar pumpkin
4 orange-fleshed sweet potatoes
1 large onion, chopped
1 1/2 quarts chicken broth