Start by placing dried red chilies like Guajillo, Pasilla, and Kashmiri in a bowl. Cover the chilies with hot water and let them soak for about 30 minutes, or until they are softened. This softening is crucial for easy blending and achieving the smooth texture of harissa.

Heat a pan over medium heat and add caraway seeds, cumin seeds, and coriander seeds. Toast them until they become aromatic, which enhances the flavor of your harissa. Watch closely to avoid burning the spices, as this can introduce a bitter flavor. Once toasted, transfer the spices to a bowl and let them cool to room temperature.

In a blender, add the drained, softened chilies (seeds can be removed at this point to reduce heat), roasted bell peppers, paprika, cayenne pepper, garlic, the toasted spices, white vinegar, lemon juice, salt, and olive oil. Secure the lid tightly.

Blend on high speed until you achieve a smooth paste. Pause occasionally to scrape down any ingredients that stick to the sides, ensuring an even consistency.

After blending, check the consistency of the harissa. If it's too thick, add a little water to achieve a sauce-like texture. Carefully transfer the harissa from the blender using a spoon or spatula to avoid direct contact with your skin. To ensure no paste is wasted, add a bit of water to the blender jar, swirl it to collect any remaining paste, and mix it into your harissa for further adjustment.