Heat oil in a large pot, cook onion, carrot, and celery for 5 minutes. Add garlic, ginger, and curry paste; cook 30 seconds.
Add stock, lentils, and rice. Bring to a boil.
Reduce heat and simmer 10 minutes until lentils soften.
Stir in chicken and spinach; cook 7 minutes more.
Add lemon juice and salt to taste. Rest a few minutes before serving.
