7 ounce Yukon Gold or white potato, peeled
3 T butter, plus more to finish
2 large onions, thinly sliced
4 garlic cloves, minced
1-3/4 inch piece ginger, peeled and grated
1 pound eggplant, peeled and cut into 1/4-inch cubes
14 ounces strained or crushed tomatoes
1/2 head cauliflower (about 9 ounces), chopped into small pieces
1 T tomato paste
2 tsp ground cumin
2 tsp ground coriander
1/2 tsp kosher salt
1 tsp garam masala
1/4 tsp turmeric
Soft white bread rolls
1. Chop the potatoes into chunks, and boil until tender (10-15 minutes). Drain, mash, and set aside.
2. Melt the butter in a large skillet. Add the onions, and stir until softened and golden, around 25-30 minutes. Add the garlic and ginger, and cook for a minute or so. Add the eggplant and cover. Stir occasionally for about 10 minutes, until softened. Add the tomatoes, cauliflower, and tomato paste. Cook for 5-7 minutes, covered, until everything is nicely combined. Add more water if needed to get the mash to a loose consistency.
3. Add the spices (cumin, coriander, salt, garam masala, and turmeric), along with the reserved mashed potato. Stir everything together and cook, covered, for 10 minutes or so.
4. Use a potato masher to mash everything together, adding more water to get the consistency you want -- up to your taste, but you want something between mashed potatoes and thick pasta sauce. Finally, add a pat of butter and stir into the mash. Taste and adjust seasoning.
5. To serve, toast the rolls and spread with butter. Add a scoop of the mash, and then top with cilantro and squeeze lemon juice over everything.