Start by preparing your sauces.
For the chimichurri, finely chop all ingredients and stir through vinegar and olive oil.
For the harissa mayo, mix the harissa paste and mayonnaise together. Set aside.
Grill the chorizo sausages until cooked through (BBQ or hot griddle pan).
Slice in half lengthwise and grill for another minute for extra colour. Set aside.
Toast the buns on the same grill.
To assemble, spread harissa mayo on the base of the bun.
Add the grilled chorizo and spoon over chimichurri.