For the mango-pineapple relish, peel the pineapple and remove the woody stalk. Cut into small cubes. Peel the mangoes and finely dice the flesh as well. Peel and finely chop the onions. Slit the chili peppers lengthwise and remove the stalk and seeds. Cut into fine strips. Peel and finely chop the ginger root and garlic. Wash the lime with hot water, rub dry and finely grate 1 tsp of zest. Squeeze the juice from the lime.
Roast the mustard seeds in a pan without adding any fat. Now put all the ingredients (except the alcohol) in a saucepan and bring to a boil. Reduce heat and simmer over medium heat for 50 minutes. The relish is ready when it has thickened slightly. You can drag a wooden spoon handle across the bottom of the pot as a test – you want a trace to remain visible.
While still hot, pour the mango-pineapple relish into prepared jars, drizzle a few drops of alcohol over the top, light and seal tightly.