1.Place kumara on a microwave-safe plate. Microwave on High (100%) for 5 minutes or until just tender. Transfer to a heatproof bowl. Using a fork, mash until smooth. Cool.
2.Add baked beans, half the onion, the tuna and breadcrumbs to kumara mash; stir to combine. Shape mixture into 12 patties. Coat patties in flour, shaking off excess. Transfer to a baking tray lined with baking paper.
3.Heat oil in a frying pan over medium-high heat. Cook patties, in 3 batches, for 5 minutes or until golden and heated.
4.Combine remaining onion, tomato, cucumber and dressing in a bowl. Serve patties with tomato salad.
You can use canned pink salmon instead of tuna if you like.