Something like this?

I used random steps
decorator for the green path, and "manually" built the black path, using some key points and start/end angles. Also note the use of polar coordinates, which are more appropiate for this case than cartesian ones.
\documentclass{standalone}
\usepackage{tikz}
\usetikzlibrary{decorations.pathmorphing,shapes.geometric}
\colorlet{myred}{red!60!black}
\colorlet{mygreen}{green!40!black}
\begin{document}
\begin{tikzpicture}[scale=0.7]
\node[draw=myred, ellipse, minimum width=3cm, minimum height=4.5cm] (e1) {};
\draw[myred, ->] (e1.-30) -- +(-20:2) node[right] {$\Omega_0$};
\node[draw=mygreen, ellipse, minimum width=3.8cm, minimum height=5.2cm,
decoration={random steps, segment length=1.5mm}, decorate]
(e2) {};
\draw[mygreen, ->] (e2.0) -- +(5:1.5) node[right] {$\widetilde\Omega_0$};
\draw[mygreen, <-] (e2.90) -- +(80:.5) node[right] {$v_\varepsilon=0$};
\draw (0:3) to[out=90,in=-65] (45:4)
to[out=180-65,in=0] (90:5)
to[out=180, in=180-70] (150:4.5)
to[out=-70, in=90] (190:3.2)
to[out=-90, in=180-50] (234:5.1)
to[out=-50, in=180] (280:5.3)
to[out=0, in=-45] (-30:4)
to[out=180-45, in=-90] (0:3) -- cycle;
\draw[->] (50:4.2) -- +(30:1) node[right] {$\Omega$};
\draw[<-] (85:5) -- +(85:1) node[right] {$u_\varepsilon=0$};
\end{tikzpicture}
\end{document}
curve through
keyword, which is not standard tikz. Which package comes it from? Anyway, "fixing" it by replacing by aplot[smooth cycle] coordinates {...}
it results in a figure which is not related to the drawing you pasted. For example, what is the magenta circle?