Heat oil in a large skillet or Dutch oven over medium heat until shimmering.
Add potatoes and cook, stirring occasionally, until lightly browned, about 3 minutes.
Stir in onion and cook until softened, about 2 minutes.
Add curry paste, tomato sauce, and coconut milk. Stir to combine, reduce heat to medium-low, and simmer until potatoes are fork-tender, 8-10 minutes.
Stir in chickpeas and peanut butter until the peanut butter is fully incorporated and the sauce is creamy, about 2 minutes.
Season with salt and pepper. Garnish with cilantro and serve hot over rice or with flatbread.
