Combine the vinegar, mustard, brown sugar, ketchup, orange zest and salt.

With an immersion blender running, slowly add the oil until the dressing has thickened up. If you prefer a thicker dressing, add one extra tablespoon of ketchup.

In a large bowl, combine the grapefruit, orange, almonds and mixed greens.

Toss salad with dressing and top with tongue slices.