To a blender, add the strawberry jam, sherry vinegar, lemon zest and juice, garlic, mustard, sriracha and salt. Blend well. With the motor running, slowly add the oil in a steady stream until the vinaigrette is emulsified and thick.
Melt the butter with the agave in a skillet over medium-high heat. Add the sunflower seeds, stirring to coat. Transfer to a parchment-lined baking sheet and sprinkle with the sea salt. Roast for 5 to 7 minutes, stirring halfway through. Remove from the oven, and let cool completely.
Arrange the arugula on a large serving platter. Scatter with the candied sunflower seeds, and drizzle with 1/2 cup of the dressing. Serve immediately.