Place the peas in a small pan of boiling water and simmer until just cooked. Leave to drain and dry slightly in a colander or sieve. Using the same warm pan, dried of any water, wilt the spinach. (If using frozen spinach, defrost fully and squeeze out all the water; for chard or kale, cook for 5–10 minutes with a splash of water until completely softened.)
In a small dry pan, toast the cumin seeds over medium–high heat until their aroma is just released. Add the gram flour and toast for another minute. Transfer to a large bowl and set aside.
To the same pan, add the ginger, chillies and a teaspoon of the oil. Cook over low–medium heat for 2–3 minutes.
Meanwhile, add the peas, cooked greens and fresh coriander to a blender or food processor and blitz to a rough paste. (If using kale, this may require extra blending to make it smooth.)
Add the green paste to the large bowl with the cumin and gram flour, then add the mashed sweet potatoes, ginger mixture, chaat masala powder and salt. Mix really well using your hands.
Shape the mixture into 10–12 small patties, approximately 2 cm/¾ inch thick and 6.5 cm/2½ inch diameter. Arrange on the lined baking sheet and place in the fridge for 30–60 minutes to set.
Prepare the chaat salad by mixing all the ingredients together, except the fresh herbs and chaat powder. Set aside.
Place a large non-stick frying pan over medium-high heat. Add ½ tablespoon coconut oil to the pan, then place the cutlets into the pan, cooking in two batches if needed. Reduce the heat to medium and cook for 3–4 minutes on each side until golden brown. Add a little more oil to the pan if needed.
To serve, add the fresh herbs to the salad and mix well. Place a couple of cutlets on each plate (or use one big platter). Top each cutlet with a heaped tablespoon of the salad, and sprinkle the top of each portion with a generous pinch of chaat masala powder. Serve with coriander yogurt and lemon wedges.