Start with whole spices
Buy from a shop with a high spice turnover. Look for unblemished, unbroken spices. If they are sold in bulk, smell them. They should be aromatic. Store whole spices in a sealed container, in a dry, cool spot for up to a year. Ground spices lose their flavor more quickly, after a few months.
Spices that can be toasted to good effect include peppercorns, star anise, cinnamon, cumin, coriander, juniper berries, clove, mustard seeds, and fennel seeds.
Heat a small pan over a medium heat
Add the amount of spices that you’ll need to the pan and shake it or stir the spices to prevent burning. Smaller spices and spices with thin skins need just a minute, larger ones take a few minutes longer.
They are done when they start to smell fragrant and toasty
You’ll see lighter spices take on a little bit of color. The lower left is untoasted coriander. To the right is toasted lightly. Above them is approaching burnt. Depending on the dish and your preference, you can toast spices anywhere in between.
Some seeds will tell you they are done by moving around a bit or jumping in the pan. But a rich, toasted scent is the most reliable indicator. If spices begin to smoke, you’ve gone too far.
Remove from heat to prevent over-toasting
Small spices, especially, can go from perfectly toasted to burnt in the time it takes to turn away and get a dish out of the cabinet. Have a little ramekin ready so you can remove the spices from the hot pan and quickly stop the cooking process.
Option 1: Leave them whole
Delicate toasted whole spices like cumin, caraway, and fennel can be eaten whole and add texture to a dish. Whole toasted cumin seeds sprinkled over a rice pilaf, for example, adds visual appeal, a touch of crunch, and is not overwhelming to spice-phobic taste buds. You can also use whole toasted spices when making pickles.
If you’ve toasted more spices than you need right away, you can leave them whole and save them for use within a week or two.
Option 2: Crush them
Sometimes you might want the effect of biting into cracked spices like black peppercorn or coriander. Toasting spices crisps them up, making them much easier to bite into. You can add cracked toasted black pepper to a simple macaroni or potato salad and raise the bar on your next picnic.
To make cracked spices, put them in a freezer Ziploc bag and crush them with a rolling pin, pan, or the flat side of a mallet. Or you could use a mortar and pestle, if you have one.
By the way, cracked spices work especially well in rubs for roasted or grilled meats, but they’ll toast as the meat cooks—no need to pre-toast.
Option 3: Grind them
Toasted and ground spices work well in baked goods, in dressings, added to some dredging flour, or to contribute some toasty notes to spices introduced earlier in a curry or stew.
Let the spices cool before grinding them to keep the volatile aromas from disappearing into thin air. You can use a mortar and pestle, spice mill, or coffee grinder (reserved just for spices) to grind spices down to the granularity you want. To get really fine particles, sift the ground spices.
Some spices, like cinnamon sticks, are not so easy to grind at home. In such cases, you may be better off with a small amount of newly purchased ground spice.