If you have entered into a contract, wouldn't the easiest thing be simply to settle it?
If any party is owed money they have a choice to pursue the debt. Common sense (and that isn't always the driving motivation) would suggest it depends on the size of the debt and the reasonable likelyhood of recovery. There are international treaties (for example, the Hague Convention on the Service Abroad of Judicial and Extra Judicial Documents in Civil and Commercial Matters and the New york convention on the Recognition and Enforcement of Foreign Arbitral Awards, Foreign Judgments (Reciprocal Enforcement) Act 1933, etc.) that enable process, judgments and awards in one contracting state to be enforced in another. Then there is the possibility that the breach of contract would be the causal action basis for bringing a claim in your home country. If it is a route you are considering, then it would seem to warrant specialized professional advice well beyond that you are likely to find on an internet bulletin board.
Some countries regard this type of debt as a criminal matter rather than simply a civil one. This invites the potential problems that might be encountered in travelling to other countries that might share co-operation treaties or agreements that could affect you adversely.
Dismissing this, there is then the problem likely to be encountered should you ever need to provide a reference from the aggrieved ex-employer.
Then there are secondary issues that people rarely consider. For example if you are ever arrested anywhere (even if it is only for 10 minutes and you are subsequently released,) you will encounter problems with visa rules for entering certain countries (for example the USA.)
As I said at the start, wouldn't the easiest thing be to simply settle the contract, or negotiate a settlement of the contract?