Combine the split peas, garlic, mint and a pinch of salt in a medium saucepan of water. Bring to the boil, reduce to a simmer and cook, stirring occasionally, for 30 minutes or until the split peas are tender. Drain; discard the mint.
Meanwhile, heat the oil in a small frying pan over low heat. Add the ground coriander, cumin and a pinch of cayenne pepper, and cook for 30 seconds or until fragrant.
Transfer the spiced oil to a medium bowl and whisk in the lime juice. Add the hot split peas, the chopped coriander and tomato, tossing well. Serve warm or chilled.