Yes, broth can be made in a microwave or a slow cooker. Microwaving is faster but yields less depth of flavor, while slow cooking takes longer but extracts more flavor.
Making broth in a microwave is a quick and convenient option, especially for small batches. Simply combine your ingredients (bones, vegetables, herbs, and water) in a microwave-safe bowl or container. Microwave on high for a few minutes to bring it to a simmer, then reduce the power to medium and continue cooking for 30-60 minutes, or until the broth has reached your desired flavor. The microwave method is best for when you need broth quickly and aren't overly concerned with achieving the richest possible flavor.
Using a slow cooker to make broth is a low-effort, hands-off approach that allows for maximum flavor extraction. Place your ingredients in the slow cooker, cover with water, and cook on low for 6-12 hours, or even longer. The long, slow cooking process gently simmers the ingredients, drawing out deep, complex flavors. This method is ideal for making large batches of broth and for using up leftover bones and vegetable scraps.
The limitations of microwaving broth include a less developed flavor profile due to the shorter cooking time and potential for uneven heating. With a slow cooker, the main limitation is the extended cooking time, which requires planning ahead. Also, be mindful of the size of your slow cooker to avoid overfilling.
When making broth in either the microwave or slow cooker, avoid adding salt at the beginning. Salt can inhibit the extraction of flavors from the bones and vegetables. Instead, season the broth to taste after it has finished cooking and been strained.