Wash the mint and parsley. Remove leaves from mint to equal ⅓ of a cup.
Add yogurt, mint, parsley, salt, and juice from half a small lemon to a blender.
Blend or pulse until yogurt sauce reaches desired consistency and herbs are blended into the yogurt. (See NOTES below about blending)
Notes
The thickness of your sauce will depend on how much you blend the sauce and the thickness of your yogurt. For a thinner sauce, blend more. For a thicker sauce, pulse to incorporate everything. You can also mince the parley and mint and simply stir to combine rather than blending.
While you can use the sauce as a marinade, I much prefer it as a drizzling sauce so it keeps all the flavors.
The sauce can be stored in an airtight container in the refrigerator for 3-4 days.