Cut the courgette, aubergine, and bell pepper into slices and fry them in an oiled and well-heated griddle pan. Season the vegetables with salt.
Fry the burgers in a griddle pan in hot oil. Fry the burgers for 4-5 minutes on each side, occasionally flipping them.
Season the baby leaf salad mix with a bit of salt and freshly squeezed lemon juice.
Slice the buns and spread the sauce on the bottom half. Layer the burger on top of the sauce, followed by the courgette, aubergine, and bell pepper. Top with the dressed baby leaf salad mix.
Place the top of the bun on the burger and serve.