As the congee cooks, wash the clams in a large bowl of water and scrub with a brush. Remove any clams that are opened. Drain the water and repeat scrubbing and rinsing until the water runs clear.
When the congee only has 10 minutes left to cook (or is already done) begin cooking the clams. Heat 2 tbsp oil in a saucepan (with a lid) over medium heat. Add the shallots and fermented black beans and cook for one minute, stirring frequently. Add the ginger, garlic, and scallion whites and cook for 30 seconds.
Add the clams. Pour in shaoxing wine and immediately cover the pan. Reduce the heat to low, letting the clams steam 5-8 minutes until the shells all open.
Remove from heat and plate the clams, leaving the liquid in the pan. Top clams with lemon for squeezing and garnish with cilantro leaves. Pour the liquid in the pan into the pot of congee, stir. Garnish congee with scallion greens. Serve immediately.