Coarsely chop a shallot into small pieces and add it to a blender. Shallots have a mild flavor that is somewhere in between onions and garlic, but if you don't have shallots you can use half an onion instead.
1 Shallot
Also add finely chopped thai green chillies. These can be substituted with any other green chilli as well.
2 Thai Green Chillies
Wash the thai basil leaves, remove the leaves from the stems and add to the blender. Thai basil has a sweeter taste than Italian basil, but if you can't find thai basil (brown stems) then you can use mint & Italian basil instead.
1/2 Cup Thai Basil Leaves
Also add coarsely chop coriander leaves. You can remove the thick part of the stem.
1/2 Cup Coriander Leaves (Cilantro or Dhaniya)
Next step is to prepare the lemongrass. Trim off the top portion of the lemongrass stalk that has the roots. Then peel off the outer 2-3 layers till you reach the soft fleshy part inside. Remove the leaves part and chop the firm white portion (top 3Ams -4 inches) into small pieces to add to the blender.
2 Lemongrass Stalks
Add garlic cloves, ginger and lime zest. Also add a little bit of lime juice. The traditional ingredient added to the curry is Galangal which is similar to Ginger, but slightly stronger in taste. I have used ginger since I couldn't find galangal. I have also substituted kefir lime leaves with lime zest, which is very similar in flavor.
3 Garlic Cloves, 1 Inch Piece of Galangal, 3-4 Kefir Lime leaves, 1 Tablespoon Lime Juice
Dry roast cumin seeds and coriander seeds on low-medium heat till they start to brown and give an aroma.
1 Teaspoon Cumin Seeds (Jeera), 1 Teaspoon Coriander Seeds (Sabut Dhaniya)
Let them cool down slightly and then grind them to a coarse powder.
Add all the ingredients in a blender along with peppercorns & salt and grind them to a smooth paste. If needed, you can add a tablespoon of water.
8-10 Black Peppercorn (Sabut Kali Mirch), 1 Teaspoon Salt
Green curry paste is ready. You can use it to make the curry, or store in the refrigerator for later use.