Replace one value by multiple values

Classic wdx223_Daniel! Brilliant solution but takes effort to understand.

I think I've deciphered it and this is my annotated translation of it that may help future readers follow along too:

let
  Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("i45WclTSUUoEYgM9U6VYHQg/CYkPkssF803g/Dww3wzMB8lVgPmWcH4VmG+oFBsLAA==", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [Product = _t, Ingredients = _t, Weight = _t]),
  tbl = Table.Buffer(Source),
  /*Define recursive lookup function.*/
  fx =
    (L as list) => // {lookup, (optional) ingredient, (optional) weight}
    let
      lookup     = L{0},  // 1st item in list
      ingredient = L{1}?, // 2nd item in list or else null
      weight     = L{2}?, // 3rd item in list or else null
      /*Lookup ingredient row in tbl or return null*/
      row = tbl{[Ingredients = lookup]}?,
      recursive_step =
        if row = null
        then L // End recursion
        else   // Recursively call fx on new values
          @fx(
            {
              row[Product],                            // new lookup
              ingredient ?? row[Ingredients],          // new ingredient
            /*List.Product({row[Weight], weight}),     // multiply weights*/
              Text.Combine({row[Weight], weight}, "*") // concatenate weights
            }
          )
    in
      recursive_step,
  /*Ingredients not appearing in the [Product] column*/
  leaf_ingredients = List.RemoveItems(tbl[Ingredients], tbl[Product]),
  /*Apply recursive lookup function to each leaf ingredient.
    Each ingredient becomes {Product, ingredient, weights}.*/
  tbl_rows = List.Transform(leaf_ingredients, each fx({_})),
  col_names = Table.ColumnNames(tbl),
  /*Construct table from column names and list of rows*/
  result = #table(col_names, tbl_rows)
in
  result