To make the salsa, combine all the ingredients in a bowl and set aside to allow the flavours to marry together.
Heat the olive oil in a large sauté pan over a medium heat. Sauté the onion and garlic for 8–10 minutes, or until golden, soft and fragrant.
Add 2 cups of the beans along with all the spices. Stir in the sauté pan until everything is warmed through.
Preheat your oven grill.
Add the oats to the bowl of a food processor and pulse them a few times. Add the onion, garlic and bean mixture. Process everything together until it’s well combined but still has some texture.
Transfer to a mixing bowl. Add the rest of the black beans and the corn and mix well with your hands. Check for seasoning. If the mixture is too mushy to form into patties, add a little more oats or breadcrumbs.
Lightly oil a baking sheet or line it with parchment paper. Shape the mixture into 4 large or 6 smaller patties. Transfer the burgers to the sheet and grill for 8–10 minutes per side, until golden. You can also pan-fry them in light olive oil until golden on each side.
Serve in a bun with the tomato salsa and any topping of your choice.