Peel and cut potatoes into 2 cm small cubes and boil until soft.
Cut the beans into 3 cm lengths then blanch in boiling water for a couple of minutes.
Make the pistachio pesto by adding 2 cups of basil, 1/4 cup pistachio nuts and olive oil to the blender and blitz until smooth. Remove from the blender and put into a bowl. Season the mix with salt & pepper and add the parmesan and lime juice.
Toss the beans and potato through the pesto until evenly coated them put aside in the fridge.
Brush the Tuna steaks with olive oil and a light dusting of Coffee Rub and cook on the BBQ until approx. 55°c-60°c this will be medium rare.
To serve, place a small pile of potato salad on a plate and stack the tuna steaks on top.