Here's a coleslaw recipe that doesn't use mayo. You can set it on a pack of blue ice for the trip, but it won't spoil out of refrigeration. This will serve about 10.
1 head of cabbage
1 1/2 ts salt
1 large sweet red pepper, sliced into 2” strips
2 ts lime zest, from one or two limes
4 tb fresh lime juice
2 tb rice wine vinegar or sherry vinegar
1/2 ts cayenne pepper
2 ts ground cumin
2 tb honey
2 tb extra virgin olive oil
Core and thinly slice cabbage. Salt with 1 1/2 ts of salt and set aside in a colander over a bowl for an hour to drain. Rinse salt off and pat cabbage dry. Put the shredded cabbage into a bowl. Add sweet pepper. Stir together lime zest and juice, vinegar, cayenne, cumin, honey and oil in medium bowl. Toss cabbage and peppers in dressing, season to taste with salt and pepper. Serve chilled.
Here's a dessert if you're interested:
Pucker Up Crisps
1 cup sugar
1/4 cup lemon juice
4 tb unsalted butter, room temperature
2 tb heavy cream
1/2 ts lemon oil
1 tb grated lemon zest
1/2 ts baking soda
1 cup cake flour
1 cup toasted, ground whole almonds with skins
In a small saucepan, dissolve 1/4 cup of the sugar in the lemon juice over medium heat. Simmer until it thickens slightly, about 1 minute. Add the butter, stirring just until melted. Remove from heat and transfer the mixture to a bowl. Add the cream, lemon oil, remaining 3/4 cup sugar, lemon zest, baking soda, flour, and almonds and mix well. Refrigerate for 1 hour, until well chilled. Preheat the oven to 350º.
On a lightly floured surface, roll out the dough 1/8-inch thick. Cut into strips, 1 1/2 inches wide. Cut 1 1/2 inch wide strips on the diagonal in the opposite direction, to make diamond shapes. Transfer the crisps to a parchment-lined baking sheet and bake until lightly golden on the edges, 8 to 10 minutes. While baking, the crisps will puff and crack slightly. Remove from the pan and cool on a rack before serving. When they are cool, they will be crisp.