Arrange salmon fillets, asparagus, zucchini, and sweet pepper on two 9x13 double-thickness sheets of tin foil.
In a small bowl, whisk lemon juice, olive oil, mustard, agave, dill, and salt and pepper to taste. Pour evenly over both packets of salmon and veggies. Fold up foil packets tightly to seal.
Grill foil packets over medium-high heat, turning occasionally until salmon is flaky and pink and veggies are tender, about 10 minutes. Remove from grill, cool slightly, and serve warm. Enjoy!