Place the chopped onion in a small bowl with the juice of 1 lime and season lightly with salt. Set aside to marinate while the potatoes cook.
Cook and mash the potatoes, let cool down. Mix with chilli paste, juice of 3 limes, macadamia oil and salt.
Slice mushrooms and sautée in olive oil. Let cool down, mix with mayonnaise (method below).
Oil a ring mold. Press half of the mashed potato mixture into the bottom of the pan. Cover with the mushroom mixture in a smooth layer. Top with slices of avocado. Layer the other half of the potato mixture on top and smooth the potatoes with the back of a spoon. Top with slices of heart of palm and olives.
Serve chilled with lettuce leaves and cherry tomatoes.