Combine lemon juice, cilantro, garlic, pepper flakes, oregano, and canola oil in a blender. Process to form a thick puree.
Taste and season with salt, as desired. Store in an airtight container and refrigerate until needed. For best results, make on same day serving.
Usage: Save ⅓ cup chimichurri as a marinade and reserve ⅔ cup to use as a sauce for beef, chicken or meaty fish such as tuna and salmon. Marinate beef and chicken up to 4 hours or overnight, and fish up to 1 hour. Discard marinade after using. Grill proteins over medium-high heat.