Classic Argentine chimichurri is built on parsley, but fennel fronds make a genuinely good substitute - the anise-sweet note they bring gives the sauce a slightly different, distinctly good character while keeping the same basic garlicky, herby structure.
Prep time: 10 minutes | Makes: about 1 cup
Chimichurri is meant to be a loose, oily sauce rather than a smooth puree - chop by hand rather than using a food processor for the right rustic texture.
A small amount of parsley alongside the fennel fronds keeps the sauce closer to a traditional chimichurri's herbal backbone, while the fronds add their own distinct anise-sweet layer on top. Using fronds alone works too, but the result leans more toward a fennel-forward herb sauce than a true chimichurri variation.
Chimichurri is classically served over grilled steak, but it works just as well over grilled or roasted fish, chicken, or roasted vegetables. It also makes a good marinade if used a few hours before cooking, in addition to its more common role as a finishing sauce.
This is a good example of fronds working in a savory, garlicky context rather than only a delicate one. For more, see the complete fennel fronds guide.