For the dressing

4 tbsp lime juice
7 tbsp extra virgin olive oil
3-4 jalapeño peppers (or 1 red chilli), finely chopped, to taste
1 garlic clove, minced
pinch ground cumin
salt and freshly ground black pepper

For the salad

3 x 400g tins cooked black beans, drained
large handful chopped fresh coriander
4 medium tomatoes, chopped into wedges, seeds removed (or 16 cherry tomatoes, halved)
1 large red pepper, stalk and seeds removed, sliced into thin strips
1 red onion, thinly sliced
5 spring onions, trimmed and thinly sliced (or 1 small red onion, thinly sliced)
200g/7oz fresh watercress, tough stems snipped into half
2 large ripe avocados, skin and seeds removed, cut into cubes