You can add a roasted flavor to broth by toasting spices, adding a small amount of browned stock from a previous batch, or incorporating ingredients like roasted garlic or tomato paste. These techniques introduce the Maillard reaction flavors associated with roasting.
When you roast ingredients before making broth, you're essentially creating complex flavors through the Maillard reaction and caramelization. If you skipped this step, you can still achieve a similar effect using several methods:
Toast Spices: Dry-toasting spices like cumin, coriander, fennel seeds, or peppercorns in a dry pan over medium heat until fragrant releases their essential oils and creates a deeper, more complex flavor profile. Add these toasted spices to your broth during the simmering process.
Add Browned Stock: If you have any leftover stock from a previous batch that was made with roasted ingredients, adding a small amount to your current broth can impart a roasted flavor. Think of it as a concentrated flavor booster.
Incorporate Roasted Garlic: Roasting garlic mellows its harshness and brings out a sweet, nutty flavor. Add a few cloves of roasted garlic to your broth for depth.
Use Tomato Paste: Tomato paste, when caramelized, develops a rich, umami flavor. Sauté a tablespoon or two of tomato paste in a little oil until it darkens slightly before adding it to the broth. Be careful not to burn it.
Liquid Smoke (Use Sparingly): A tiny drop of liquid smoke can mimic the smoky notes of roasting, but use it very sparingly as it can easily overpower the broth. Start with a single drop and taste before adding more.
Mushroom Powder: Dried mushroom powder, especially varieties like porcini, can add an earthy, umami depth that approximates the savory notes of roasted vegetables.
When toasting spices, keep a close eye on them and stir frequently. They can burn quickly, which will result in a bitter flavor. Remove them from the heat as soon as they become fragrant and slightly darker in color.