In a large saucepan over medium heat, add the oil. When the oil is hot add the onions, garlic and curry powder and saute until the onions are translucent. Add the chicken cubes and saute until cooked through. Stir in the carrots, cauliflower, potatoes, and celery and continue cooking for 5 minutes more. Add the tomato paste and flour and stir until incorporated. Pour in the chicken stock and coconut milk and stir until mixed thoroughly. Reduce the heat to a simmer, season with salt and pepper, to taste, and cook for another 30 minutes.
At this point, check to see if the vegetables are cooked through and tender. To finish add the cilantro and adjust seasoning with salt and pepper. Transfer to a serving bowl and serve with cooked rice, if desired.
Cook's Note: for additional sweetness, shredded coconut can be toasted and served as a garnish. Also, if the curry seems a little thin, it can be thickened with a little cornstarch.