In a medium bowl, combine parsley, mint, onion, courgette, cucumber, tomatoes, 60ml olive oil, lemon juice, lemon zest, salt, and pepper. Cover and refrigerate for 30 minutes up to overnight.
Drizzle 2 tsps olive oil in Instant Pot and add millet on top in an even layer. Add stock and then secure the lid.
Select Pressure Cook and set the time for 10 minutes.
When the cooking program has finished, let the pressure release naturally for 5 minutes, then quick-release any remaining pressure until float valve drops and then unlock lid.
Transfer millet to a serving bowl and set aside to cool. When cooled, add to refrigerated mixture and stir before serving.