Place potatoes on baking sheet and cover with foil. Bake for 40 - 45 minutes, or until easily pierced with a knife.
Remove potatoes from oven and allow to cool. Carefully remove thin skin and discard.
In a sauté pan over medium heat, cook diced onion and minced garlic in olive oil until soft, about 6 – 8 minutes. Remove from heat and set aside.
In a medium bowl, smash beans and potatoes with a potato masher, then add sun-dried tomatoes, basil, onion/garlic mixture, salt and pepper.
Using a half cup measure or scoop, portion 6 burgers and form into patties.
Place patties on a lightly oiled, parchment-lined baking sheet.
Bake for 10 minutes, flip and bake an additional 8 minutes.
Notes
I left a few small chunks of potato in the mixture for texture. If you want your burger to be completely smooth, pulse the mixture in the food processor to break it up completely.