Coarsely chop ½ a bunch of cilantro (stems and leaves) and coarsely chop leaves from 1 small bunch mint until you have ½ a cup.
Place in a mini food processor or blender, add lime juice, ½ serrano chili (or Thai bird chili, if using) and 1 tsp sea salt.
Process, scraping down sides as needed, until chutney is smooth. If you prefer a thinner consistency, add ice water, a tablespoonful at a time until you reach the desired consistency.