King of all curries! This wonderful dish is the final frontier for all you spicy food gourmands. This curry will make you sweat, but is still one of the most flavorful dishes you'll ever enjoy. If you can't find lal mirchi pepper, use cayenne pepper; if you can't find jwala peppers, substitute serrano chiles. Serve with basmati rice and raita.
Heat ghee in a large heavy skillet over medium heat and cook and stir red onion in the hot butter until starting to brown, about 8 minutes; stir in garlic and fresh ginger and cook, stirring constantly, until fragrant, about 1 more minute. Stir in chicken pieces and cook and stir until lightly golden brown, about 10 more minutes.
Mix ground fennel, lal mirchi, cumin, coriander, ground ginger, fenugreek, turmeric, cardamom, cinnamon, cloves, and black pepper in a bowl with 1 to 2 tablespoons water or as needed to make a paste; stir into the chicken and fry spice paste for 2 minutes. Pour in remaining 1/4 cup water and fry the spices and chicken until the water has almost evaporated, 7 to 8 minutes, stirring constantly to prevent spices from burning.
Mix in jwala chiles, habanero chiles, and tomatoes; cook, stirring often, until tomatoes are softened and start to break apart, about 10 minutes. If chicken is still slightly pink inside, stir in more water, a tablespoon at a time, and cook until water has evaporated and chicken is cooked through.