Cook the chickpeas conventionally or at 15 PSI in your pressure cooker for 5 minutes with the lemon and salt. Use natural release. Reserve liquid.
Coat a soup pot with oil. Fry the spices for just a moment, until they are fragrant but not smoky. Add the onion and sweat for 15 minutes over low heat. Add garlic and ginger and continue cooking. Add diced celeriac and saute for several minutes, stirring occasionally. Add just enough bean broth to simmer the celeriac, about 15 minutes. Add the chickpeas and only enough additional broth to simmer for a few minutes before serving.
Garnish with fresh tomatoes and chopped cilantro.