Heat 1 tbs oil in a large deep frypan over medium-high heat. Cook onion, stirring occasionally, for 2 minutes or until golden.
Add the curry paste and cook, stirring, for 1 minute. Add the coconut milk, lime leaves and ¼ cup (60ml) water and stir to combine. Bring to a simmer, then reduce heat to low and cook, stirring occasionally, for 5 minutes. Stir in snake beans, lime juice, fish sauce and sugar.
Meanwhile, heat remaining oil in a large non-stick frypan over high heat. Cook salmon, on one side only, for 3-4 minutes, until well golden. Flip fillets and transfer, golden-side up, to pan with sauce. Cook over low heat for 5 minutes for salmon to finish cooking (it should still be pink inside). Discard lime leaves and stir through basil and coriander.
Divide salmon and sauce between bowls. Scatter with extra herbs and chilli. Serve with lime cheeks and rice alongside.
