Add the oil and onions to a large pot or Dutch oven over medium heat and cook until the onions are caramelized. Add the minced garlic, grated ginger, and fingerling potatoes and cook for three minutes. Add the chopped carrot and vegetable broth, a pinch of salt and fresh cracked pepper, and bring to a boil.
Peel the apple, coarsely grate, and add to the pot. Peel the IdahoⓇ Russet Potatoes, cut into bite-sized chunks, and add to the pot. Simmer for 20 minutes until the potatoes are tender.
Make the roux by melting the butter in a small pan over medium heat. Add the flour and stir until the roux starts to get darker, about 5 minutes. Mix in the garam masala and curry powder and take off the heat once combined.
When the potatoes are done, add some of the hot liquid to the roux and whisk until the roux is incorporated and there are no lumps. Add roux back to the pot and bring back to a boil. Stir in the soy sauce and ketchup. Taste, and add the honey if you prefer it sweeter. Simmer for 5 to 10 minutes or until the curry has thickened. Serve with cooked Sarashina Soba Noodles or noodle of choice and garnish with fresh lime wedge and chopped cilantro.