Mix spices together in a small bowl and set aside.
Chop eggplant (you can peel the skin if you'd like) and place in a large bowl of water. Mix in 1/2 tsp salt and soak for 10 minutes.
Drain eggplants and pat dry.
Heat 1 tbsp oil in a pot over medium heat. Add eggplants and pan fry until soft, stirring occasionally. Remove eggplant from the pan.
Add remaining 1/2 tbsp oil to the pot. Add onions and a pinch of salt. Sauté until onions start to brown.
Add garlic and ginger and stir until fragrant, about 30 seconds.
Add spices and stir for 1 minute.
Add tomato paste and stir for 30 seconds to briefly toast.
Add eggplants and stir until well combined.
Add water, soy sauce, sugar, and beans. Cover, bring to a boil, then reduce heat to medium low to simmer for 15 minutes.
Whisk peanut butter and water together until smooth.
Add spinach and peanut butter mixture to the curry. Continue simmering until spinach wilts.
Turn off heat and stir in lime juice, garam masala, salt, and cilantro. Taste and add more lime juice/salt/sugar as desired.
Notes
1) You want to use a pure chili powder, not the American "chili powder" which is a blend of spices. The chili powder adds spiciness, so reduce if you're sensitive to spice. If you don't have pure chili powder, you can add 1/8 - 1/4 tsp of cayenne pepper for heat. 2) Use tamari for a gluten-free option. For a soy-free alternative (also Plant-Based Whole30 friendly), use coconut aminos* instead of soy sauce and omit the sugar.