Open the package of silken tofu and place it on a plate or colander lined with paper towels or a clean kitchen cloth. Let it sit for 10-15 minutes.
Add the tofu to a food processor with yeast flakes and blend until smooth.Then, add lemon juice and season with salt and pepper.
Transfer the tofu mixture to a large bowl. Add the flour and mix until a dough forms.
Place dough onto a floured surface and divide into two parts. Roll one part of the dough into a long log and cut at an angle into 1- to 1 1/2-inch pieces. Repeat with the remainder of the dough.
Bring a large pot of salted water to a boil. Gently drop the dumplings (in batches, if necessary, so as not to overcrowd) into the water and cook for 3-4 minutes, or until they float to the surface.
Drain the dumplings and serve with the pistachio breadcrumbs over the melted butter.
To make the breadcrumbs, combine the breadcrumbs, chopped pistachios, garlic, chilli flakes and salt in a large bowl.
Heat the olive oil in a large skillet over medium heat. Add the breadcrumb mixture and cook, stirring frequently, for 3-5 minutes, or until golden brown and toasted. Mix in the lemon zest and combine.
Notes
If your bread isn't already stale, tear it into pieces and spread them on a baking sheet. Toast in a preheated oven at 163•C (gas mark 3) for a few minutes.