Begin by preheating your oven to 400 degrees F. To make the salad, place the tomatoes, cut side up, on a baking tray and smear the cut side of the tomatoes with the garlic. Drizzle the oil on top as well, season with black pepper, and bake for 30 minutes, or until soft.
While baking, to make the sweet potato cakes, cook the potatoes in boiling water in a large saucepan for roughly 10 minutes, or until they are soft.
Next, spray a nonstick frying pan with olive oil and cook the bacon over medium heat until browned. Also, process the oats in a blender or food processor until the oats resemble coarse breadcrumbs.
After draining the potatoes, mash them, and then add the bacon, oats, and parsley and season with the pepper. After the mix is cool enough to handle, shape the potato mixture into four patties.
Over medium heat, reheat the frying pan and spray it with olive oil. Then cook the sweet potato cakes for 2-3 minutes on each side, or until they have browned.
To make the mayonnaise dressing, combine all the ingredients in bowl and mix well to combine.
When all things have finished cooking and you are ready to serve, place one sweet potato cake on each plate and top with a few spinach leaves, three tomato halves, and a dollop of mayonnaise.