Preheat the oven to 425ºF.
Cook the potatoes: Place the potatoes in a medium saucepan with enough water to cover by about 2 inches. Bring to a boil. Reduce the heat to a simmer and cook for about 10 minutes, or until just fork tender. Drain. Toss with olive oil, or lemon juice and roast for about 12 minutes, or until golden brown and crispy. Salt to taste.
Cook the aromatics: Meanwhile, heat the oil in a large saucepan over medium-high heat. Cook the onion, garlic, and ginger for about 5 minutes, or until the onion is translucent.
Add 3 tablespoons yogurt and stir to combine.
Add the tomatoes & spices: Add the chopped tomatoes, garam masala, coriander, turmeric, and cayenne. Cook for about 4 minutes, or until the tomatoes have softened, stirring frequently.
Add 1 cup water, tomato purée, and maple syrup. Mix to combine. Simmer uncovered for 5 minutes.
Add the beans & season: Stir in the beans and simmer until warmed through. Add the remaining yogurt, lime juice, and salt to taste. Garnish with cilantro.