Pour a quart of water into saucepan. Set it on the stove, and then turn up the heat to medium-high. Stir in the sea salt until it dissolves fully, and then allow the water to cool to room temperature.
Trim the cucumbers of any tough stems and flower ends, and then place them in bowl. Cover them with cold water to refresh them, at least 20 minutes and up to 1 hour.
Drain the cucumbers, and then place them into your jar. Drop in the garlic and spices, and then slide the horseradish leaf and dill into the jar. Cover the cucumbers with the saltwater brine. Place a weight over the pickles, and then seal the jar.
Allow the pickles to ferment at room temperature until they turn from vivid green to a dull green, and smell pleasantly sour - at least 1 week and up to 2 months, depending on how sour you like them.
Eat the pickles right away, or store them in the fridge up to 1 year.
Substitutions: If you don't have flowering dill, substitute about 1/2 cup fresh dill or a few tablespoons of dried dill. And if you can't find horseradish leaf, try using grape leaves, sour cherry leaves or even a spoonful of black tea.