Mix ⅓ cup medium coarse salt, 1 teaspoon dried garlic, 1 teaspoon smoked paprika, 1 teaspoon chili powder, 1 teaspoon turmeric, 1 teaspoon black pepper, ½ teaspoon dried mustard powder, ½ teaspoon fennel seeds, ½ teaspoon celery seedsand ½ teaspoon dried onion powder in an airtight glass jar. Shake to mix well. You can also mix the spices in a small bowl and transfer to the jar.
Preheat oven to 180ºC (350ºF).
Put aluminum foil in an oven tray (it makes it easier to clean up afterward).
Cut washed and dried 2 pounds medium potatoes in half, and then each half in thirds or fourths, depending on how big you want the wedges. Put them in a bowl.
Add 3 tablespoons unsalted butter, melted, and 3 tablespoons olive oil to the potatoes and mix a bit to coat the wedges. Or do this directly on the aluminum paper, careful not to tear it. You can use more oil if you feel it's not enough.
Bake for 30-40 minutes, or until they are tender inside and golden outside.
Sprinkle a few tablespoons of the spice mixture, stir to coat the wedges lightly and return to the oven for 5 more minutes, until they are crunchy and golden.
Serve immediately with another sprinkling of spiced salt.