Pat the chicken thighs dry and season them lightly with salt. Heat olive oil in a heavy-bottomed pot over medium-high heat until shimmering.
Place the chicken thighs skin-side down and sear for about 5 minutes until golden brown. Flip and sear the other side for another 4-5 minutes.
Remove the chicken and set aside. In the same pot, add sliced onion and cook for 5-7 minutes until translucent and fragrant, stirring occasionally.
Add minced garlic and ground cumin to the onions, cooking for 1 minute until fragrant and slightly toasted.
Pour in the chicken broth and add the saffron threads with its soaking water for color and aroma. Stir gently to combine.
Return the seared chicken thighs to the pot, skin-side up, and nestle them into the sauce. Slice the grilled lemon or preserved lemon and add to the pot.
Cover the pot with a lid and simmer over low heat for 35-40 minutes, letting the flavors meld and the chicken become tender.
Once the chicken is tender and the sauce has thickened slightly, remove from heat and garnish with fresh cilantro.
Serve the Moroccan chicken hot, spooning the sauce and onions around the chicken, and enjoy its rich, fragrant flavors.