Add coriander seeds and cumin seeds to a small nonstick pan and dry roast on medium heat until browned and fragrant. Keep stirring continuously.
Once done, remove the pan from the heat and keep it aside.
Roast The Bell Peppers:
Roast red bell peppers over direct flame until charred from all sides. Keep rotating while roasting using a tong.Note – You can also roast the peppers in a broiler or use jarred roasted peppers.
Remove the roasted peppers to a plate and let them cool completely.
Once cooled, peel off the charred skin.
Discard the seeds and chop them into small pieces.
Make The Sauce:
Add the chopped roasted peppers, bird’s eye chilies, olive oil, salt, garlic cloves, and lemon juice to the medium jar of a blender.
Blend to make a smooth paste.
Harissa sauce is ready. Transfer it to an airtight container and refrigerate. Use as required.