Combine 1 Tbsp of hibiscus vinegar with hibiscus simple syrup in a small bowl and mix well; set aside.
Heat a heavy 12-inch skillet or large wok over high heat for 2 minutes. When pan is hot, pour in oil and a few seconds later, add green beans, garlic and shallot. Season beans well with salt and pepper and cook, stirring often, 3 to 4 minutes.
Reduce heat to medium-low, carefully add water (it will steam) and a few seconds later add vinegar mixture. Stir beans and cover pan, leaving lid ajar. Cook until beans are tender but still have a slight crunch, about 4 minutes.
Stir in the remaining 2 tsp hibiscus vinegar. Add butter and toasted almonds and swirl pan just until butter is melted.
Season to taste with salt and pepper and serve immediately.