Heat the oil in a large skillet over medium heat until it shimmers and starts to gently bubble.
Add the chopped onion to the skillet and sauté, stirring frequently, until it becomes translucent and soft, about 5 minutes. The aroma will be sweet and fragrant as it softens.
Stir in the minced garlic and cook for another minute until fragrant, filling the kitchen with a sharp, aromatic scent.
Add the berbere spice blend to the skillet and cook, stirring constantly, for about 30 seconds to release its smoky, warm aroma.
Pour in the crushed tomatoes, stirring to combine everything into a rich, thick sauce. Let it simmer gently for 10 minutes, allowing the flavors to meld and the sauce to slightly reduce.
Season the chicken thighs generously with salt and pepper, then nestle them into the sauce, skin-side up if applicable.
Cover the skillet, reduce heat to low, and let the chicken simmer in the sauce for about 25-30 minutes, or until the meat is tender and pulls away easily from the bone.
Remove the lid and spoon some of the thickened sauce over the chicken to baste it and coat it evenly with the spices. Let it cook uncovered for another 5 minutes to deepen the flavors and slightly thicken the sauce.
Check the seasoning and adjust salt if needed. The sauce should be rich, fragrant, and cling to the tender chicken.
Garnish with fresh herbs like chopped cilantro if desired, then serve hot over injera, rice, or your favorite bread to soak up the flavorful sauce.