If you don't have both spices, it's okay to omit one or the other.
Ingredients
3 garlic cloves, crushed
3/4 cup coarsely chopped fresh cilantro
3/4 cup coarsely chopped fresh parsley
1 teaspoon ground cumin
1 teaspoon ground fenugreek
2 teaspoons kosher salt, plus more
1 cup tahini
1/4 cup fresh lemon juice
Directions
Pulse garlic, cilantro, parsley, cumin, fenugreek, and 2 teaspoons salt in a food processor until similar in texture to pesto. Add tahini and lemon juice; process 30 seconds (mixture will be very thick and gray).
With motor running, gradually drizzle in 3/4 cup water and process, adding more water to thin if needed, until sauce is light green and the consistency of sour cream. Season with salt.