Blend the ingredients. In a blender or a food processor, add all the ingredients except the oil and salt, and process to a fine paste. Alternatively, you can chop the green chili peppers, onion, garlic and ginger very finely by hand, then mix the white vinegar and lemon juice in to make a paste. Set paste aside.
Heat vegetable oil. Add vegetable oil to a medium saucepan, preferably cast-iron, and heat oil on medium to high heat.
Cook all ingredients. Once the oil is just hot, add the paste along with the salt. You know the oil is just hot when it begins shimmering. You do not want your oil to be too hot because the chili paste could burn. Cook until the green chili darkens in color, about 8 minutes. Gently mix everything. Taste and adjust the salt, white vinegar and lemon juice, if needed.
Serve. Enjoy this delicious chili paste with a variety of dishes of your choice. It, of course, goes especially well with non-spicy Mauritian dishes.
Storage. To store, let the paste come to room temperature before transferring into a container. It keeps well in the fridge for several days and the flavor will develop over time. You can top it with some vegetable oil if you would like it to last for a few weeks.