To make patties, chop and steam sweet potato over boiling water for approx. 10-12 minutes or until tender.
Transfer to a heat-proof bowl. Mash, then cool. Add the egg yolk, flour, thyme, black pepper.
Mix well to combine. Shape the mixture into 4 burger patties. Roll in the pepitas to coat.
Transfer to a baking tray lined with non-stick baking paper. Chill for approx. 30 minutes to set firm.
In the meantime, combine coconut cream, lemon zest with juice, and chilli in a bowl. Season with salt and pepper. Stand at room temperature until needed.
Preheat a large non-stick frying pan over a high heat. Brush the mushrooms all over with the combined coconut oil andgarlic.Season with salt and pepper. Cook for 4 minutes, turning once, or until just tender and golden crisp. Transfer to serving plates, cap side down.
Reduce heat to medium. Add the extra oil to pan. Cook the patties for approx. 4 minutes each side or until heated through and golden.
Place the patties on the top of the mushrooms, top with tomato, rocket and cucumber and drizzle with the coconut cream mixture to serve.
