Ina Gartner's Tuna and Hummus on Sourdough

Ingredients

• 14 ounces jarred or canned Italian tuna in olive oil
• 1/4 cup minced celery
• 2 TBSP minced yellow onion
• 2 TBSP minced cornichons
• 2 TBSP freshly squeezed lemon juice
• 2 TBSP Hellman's or Duke's mayo
• 1 tsp Dijon mustard
• 1/2 tsp kosher salt
• 1/4 tsp freshly ground black pepper
• Sourdough bread, halved and sliced 1/2 inch thick
• Hummus, store-bought or homemade (recipe follows)
• Fresh radishes, sliced
• 2 cups canned chickpeas, drained, liquid reserved (15.5-ounce can)
• 1/3 cup tahini or sesame paste
• 4 tsp minced garlic (4 cloves)
• 6 TBSP freshly squeezed lemon juice (3 lemons)
• 8 dashes hot sauce, such as Tabasco
• 2 tsp kosher salt