Heat up 2 tablespoons of olive oil in a heavy bottomed Dutch oven over medium high heat for 2 minutes. Add the onions, celery, carrots and red bell pepper, sprinkle with salt, and saute for 5 minutes, stirring with a large wooden spoon. Add the minced garlic and cook until fragrant, about 1 minute.
Mix all the spices in a bowl and add them to the pot, stirring constantly for 30 seconds to bloom the spices.
Lower the heat to medium low and add the tomato paste to the veggies. Allow it to caramelize by stirring it for 4 minutes.
Increase the heat to medium high. Deglaze the pan by pouring in 1 cup of vegetable broth and using a wooden turner to scrape off all the browned bits from the bottom of the pan.
Pour in 7 cups of vegetable broth then add the rinsed canned black beans (or 2 cups of rinsed dried beans).
Stir, then cover and bring to a boil. Reduce the heat to medium low and simmer for 30 minutes if using canned beans, or 2 ½ hours if using dried beans. (If you're using dried beans, you'll have to stir and check the liquid level as it cooks, roughly once every 30 minutes. During the last 15 minutes, taste and adjust spices, if necessary.
Remove the pot from the heat and stir in the freshly squeezed lemon juice.
Use a blender to purée 4 cups of soup. Pour the pureed mixture back into the pot and stir until well combined.
Serve hot. Panera Bread serves their soup plain, but feel free to serve with chopped cilantro, sour cream, guacamole, red onion, or tortilla chips for added color, flavor and crunch.