Make the consistency of the chili as thick as you want. Simmering the chili on low for 20-30 minutes will really bring out the flavors, but it will be on the thick side. So add additional water during the simmer to the thickness that you want.
Heat a large pan, add oil, minced onions and garlic. Cook until softened and lightly golden, about 1 minute..
Add chicken, cook chicken until it becomes white on the outside. Add fresh tomatoes, tomato paste, water, chili powder, cumin, paprika, oregano, and salt. Stir to combine well, then allow to come to simmer. Cook for about 2 minutes.
Add black beans, celery, and bell pepper. Stir to combine well. If it's too thick, add a little more water. Bring to a boil, then immediately lower heat and bring to a low simmer.
Continue simmering the chili for about 20-30 minutes, stirring occasionally, for the flavors to combine. Keep cooking the chili until it becomes your desired consistency.