\begin{tikzpicture}[node distance = 3cm, auto]
  \node [start] (init) {Create a starter};
  \node [decision, right of=init, node distance=3.5cm] (decision_start) {Starter last fed within 3~days?};
  \node [block, right of=decision_start, text width=7em, node distance=4cm] (feed_no_branch)
      {Feed starter twice:\par \qty{48}{\hour} before\par \qtyrange{6}{12}{\hour} before};
  \node [block, below of=feed_no_branch, text width=7em, node distance=2.7cm] (feed_yes_branch)
      {Feed starter \qtyrange{6}{12}{\hour} before making dough.};
  \node [block, right of=feed_no_branch, text width=7em, node distance=4cm] (high_ratio)
    {Use a 1:10:10 ratio:\par \begin{tabular}{r@{}l}
           10&~g starter,\\
          100&~g flour, \\
          100&~g water.\end{tabular}};
  \node [block, right of=feed_yes_branch, text width=7em, node distance=4cm] (low_ratio)
  {Use a 1:5:5 ratio:\par \begin{tabular}{r@{}l}
          10&~g starter,\\
          50&~g flour, \\
          50&~g water.\end{tabular}};
  \node [decision, below of=high_ratio, node distance=6cm] (size_check)
    {Bubbly? Increased in size?};
  \node [decision, below of=decision_start, node distance=6cm] (smell_check)
    {Vinegary or yogurty smell?};
  \node [success, below of=init, node distance=6cm] (make_dough)
    {Prepare dough};

  \path [line] (init) -- (decision_start);
  \path [line] (decision_start) -- node{no} (feed_no_branch);
  \path [line] (decision_start) -- node[below=2pt]{yes} (feed_yes_branch.north west);
  \path [line] (feed_yes_branch) -- (low_ratio);
  \path [line] (feed_no_branch) -- (high_ratio);
  \path [line] (high_ratio) -- node[anchor=east, above=2pt] {} ++(2.2,0) |-(size_check);
  \path [line] (low_ratio) -- (size_check);
  \path [line] (size_check) -- node{no} (feed_yes_branch.south east);
  \path [line] (size_check) -- node{yes} (smell_check);
  \path [line] (smell_check) -- node{no} (feed_yes_branch.south west);
  \path [line] (smell_check) -- node{yes} (make_dough);

  % braces
  \draw[BC]   (size_check.south) -- 
      node[below=1em]{Check if starter is ready to be used}(smell_check.south);
\end{tikzpicture}