Be ready. Have your curry base simmering on the stove. Make your spice mix. Chop all the ingredients and have them at the ready. This is going to go very fast. You don't have time to mess around.
Thaw the spinach. Drain it well.
Heat a skillet over medium heat.
Add the oil. When it shimmers add the onion and green chilies. Cook, stirring constantly, until the onions just start to brown on the edges. This takes 2-3 minutes.
Add the garlic ginger paste and cook until it stops sputtering, about 1 minute.
Lower the heat to medium low. Add the spice mix. Cook, stirring constantly, for about 30-45 seconds. You want to bloom the spices in the oil. You don't want to burn it. If you burn the spices, start again. There's no fixing it.
Add the diluted tomato paste and cilantro. Stir to combine and cook for about a minute.
Turn the heat up to medium high. Add 3 oz of the curry base. Stir to combine and cook until it it starts to crater. Little holes will appear. See the guide to Indian curries to understand what this means if you aren't sure.
Add another 6 oz of curry base. Stir to combine and cook until it craters.
Now add the remaining curry base. Cook until it craters and reduce the heat to low. Add the lamb and spinach and stir to mix. Simmer for about 5 minutes. If the curry gets too dry add a bit more curry base.
Add the fresh lemon juice. Stir to combine. Serve. Enjoy!