Combine parsley, garlic, cilantro, lemon juice, and lemon zest in a food processor.

Add one third of the olive oil and blend until the mixture starts to smooth out.

Add another third of the olive oil and red pepper flakes. Pulse until the mixture gets smoother.

Add the remaining olive oil and pulse for several minutes until the mixture is smooth and creamy.

Adjust consistency with more lemon juice or olive oil as needed.