Toast the cumin and coriander seeds in a dry skillet on medium to medium high heat until you can smell the fragrance. Usually a few minutes will do.
Place the coriander and cumin seeds in a spice grinder or mortar and grind until a powder. Add sea salt and red pepper flakes and continue to grind.
Add above mixture, ginger, smoked paprika, garam masala in a blender and mix well. Next add the oil and tomato paste and blend. Next add the cilantro leaves and continue to blend and scrape until it is a paste.
Heat saute pan to medium to medium high heat. Melt coconut oil and add diced onion. Cook until translucent. Add minced garlic and chicken and saute a few more minutes.
Add 1/3 cup masala paste, mix in with other ingredients and cook a few minutes, stirring often.
Add the stewed tomatoes and coconut milk and bring to a boil. Once boiling add lentils and reduce heat to med-med low so it is a low boil and let cook for 20-25 minutes or until lentils are tender. Stir often.
Remove from heat and fold in spinach and stir until spinach starts to wilt.
Serve wih naan or flat bread if you would like, and use the naan to scoop the chicken tikka masala.