Heat oil in a skillet on medium heat.
Add sliced onions and saute 3-4 mins til translucent.
Add garlic and ginger, cook another 1-2 mins til fragrant.
Stir in doubanjiang and 5 spice. Cook for 30ish secs - 1 min to 'wake up' the paste and spices.
Add crushed tomatoes and chicken broth, stir.
Simmer uncovered for 10m so it thickens slightly.
Stir in shredded chicken and simmer for 10-15m until the chicken is coated and heated through.
Taste and adjust with salt or sugar if needed.
Spoon warm tinga mixture onto each tostada, drizzle with crema, top with pickled onions, scallions, and cilantro.