In this work, we introduce the first benchmark for evaluating the capabilities of large language models (LLMs) in understanding and generating responses in Tunisian Arabic. To achieve this, we construct a dataset of Tunisian Arabic instructions and prompt ten widely-used LLMs that claim to support Arabic. We then assess the LLM responses through both human and LLM-based evaluations across four criteria: quality, correctness, relevance, and dialectal adherence. We analyze the agreement and correlation between these judgments and identify GPT-4o as our automated judge model based on its high correlation with human ratings, and generate a final leaderboard using this model. Our error analysis reveals that most LLMs struggle with recognizing and properly responding in Tunisian Arabic. To facilitate further research, we release our dataset, along with gold-standard human-written responses for all 744 instructions, and our evaluation framework, allowing others to benchmark their own models.