For equivalent flavor, substitute 3 times as much prepared mustard for ground mustard. Use caution in recipes where the moisture balance is critical (such as in baking recipes); the more mustard called for the greater the impact of the additional moisture. In salad dressing, sauces, marinades, egg dishes, soups, stews, meat and poultry dishes, prepared mustard is a convenient and suitable swap.
A Microplane™ or fine rasp-style grater can be used to grind small amounts of whole spices; a coffee grinder is useful for larger amounts. You can find nutmeg grinders and pepper mills in the Marketplace Department.
Queso fresco can be substituted for queso blanco in your favorite Mexican recipes; they're the same thing. Find queso fresco in the Dairy Department and in the Imported Cheese Department.
A piece of fresh bread in your brown sugar bag or canister will keep your sugar fresh and moist, but you can also invest in a sugar bear. This teddy-bear shaped piece of baked clay works similarly (it absorbs moisture from the sugar and releases it slowly over time) and is reusable. Find one in the Marketplace Department.
For the smoothest cheese sauces and soups, freshly shred or grate your cheese from a brick or block.