In a large glass bowl, combine 2 tbsp of olive oil and 3 tbsp of lemon juice squeezed from the lemons with the berbere spice, crushed garlic, ground coriander seeds, thyme, some salt and pepper. Mix thoroughly.
Pour this mixture all over the chicken. Coat all over, then cover and set aside to marinate for at least 30 minutes.
Preparing the Chicken and Potatoes
Wash and dry the new potatoes. Heat a dutch oven over medium to high heat, then add 1 tbsp of olive oil. When the oil is hot, fry the chicken to sear and brown the meat for 2 - 3 minutes per side, turning over once. When done, remove from heat and set aside.
Add the new potatoes and chopped rosemary to the dutch oven, once the chicken has been removed. Add half a tablespoon of oil if needed, and fry, stirring frequently, for 3 - 5 minutes to brown and coat the potatoes. When done, remove and set aside.
Reduce the heat setting to low-medium and then add the remaining half a tablespoon of olive oil to the dutch oven, and when hot, fry the onions and garlic until soft and translucent, and the garlic is aromatic, stirring frequently. This should take about 3 - 5 minutes.
Add the chicken stock, juice of one lemon, and mustard. Taste and season as appropriate. Then add the browned chicken, potatoes, green beans and red peppers. Stir one, then cover, and transfer to the oven.
Preheat the oven to 180 degrees centigrade (fan-assisted), 200 degrees (without fan). Cook in oven for 40 - 45 minutes.