Here’s an easy little kitchen tip for you: When the jar of Dijon mustard is empty, or nearly so, don’t just rinse it out and toss it into the recycling bin (you DO recycle your glass jars, right?). Use the jar to make a quick vinaigrette: To the jar, add 1 Tbsp. of fresh lemon juice or white-wine vinegar and a pinch of salt. Put the lid on firmly, and shake the jar to incorporate whatever mustard remains clinging to the sides. Remove the lid; add 3 Tbsp. of good olive oil and several grinds of fresh black pepper. Replace the lid and shake firmly to emulsify the vinaigrette. Add some fresh snipped herbs if you’d like. Use to dress a simple salad of fresh baby lettuces.